(
;FF[4]GM[1]
AP[DGS:1.20.5]
PC[Dragon Go Server: https://www.dragongoserver.net/]
DT[2003-10-22,2004-03-19]
GN[DaoLin-goshea-37711-20040319]
SO[https://www.dragongoserver.net/game.php?gid=37711]
PB[Gearoid (goshea)]
PW[Zhilao Hu (DaoLin)]
BR[18k]
WR[3d]
XM[335]
GC[Game ID: 37711
Game Type: GO (1:1)
Rated: Y

White Start Rating: 3d (0%) - Elo rating 2300
Black Start Rating: 18k (0%) - Elo rating 300
White End Rating: 3d (-10%) - Elo rating 2289
Black End Rating: 18k (-27%) - Elo rating 273]
OT[90 days + 1 day per move and 10 extra periods]
RU[Japanese]
SZ[19]
KM[140.0]
HA[9]
RE[W+140]
AB[pj][pp][jj][jp][dp][jd][pd][dj][dd]PL[W]
;MN[1]W[qf]
C[I wish us a nice teaching game!]
;B[qe]
;W[pf]
C[A very good move indeed, which limits white's possibilities on the right side,
because there is a side-handicap stone too!]
;B[nd]
;W[ph]
C[You did another Joseki (Chinese: ding shi) move. 
Indeed you will learn very much from the book "Basic Techniques". It's a classic.]
;B[ng]
;W[qj]
C[Your move is globally a good move. Tactically either a kosumi (diagonal move) to R11 and then, after W reacted, a tobi-1-point-jump to O10 or even a keima (hores shape play) to O11 are standard variations. W jumps usually out another time to M13 and Black defends the upper side with another kosumi N15, while attaking at the same time (esp. when the keima was played). Later I will add these variations to the SGF-file, because a picture tells more than 1000 words!]
;B[qk]
;W[qi]
C[Yes, very normal. If you cannot cut or kill your partner's stones, confine them.
Go is about separating and killing other stones and connecting your own's. Your move confines me. 
A cutting point at Q9 remains for you. Do you connect it and how? Or do you prefer to tenuki (play somewhere else) and take sente (tempo)? Would connecting be sente (to kill or severely harm white's group)? You see, we played only a few moves and there are many questions. The questions will multiply AND become more complex.]
;B[pk]
;W[cn]
C[Yes, your last move is perfect for indirectly protecting the corner.
I call this the inverse-Clausewitz quotation "Defense is the best attack!".
The profit you'll make by this is most probably bigger than other moves on the board in regions where you are already strong anyway!

And a nice, additional advantage is, that my white stones there become vulnerable. I still can escape to the center (but escaping ALONE does not create territory) and I still can do some hane (bending around) on either side. 
But ... what if you do a hane (and then connection) or a simple stretch-down on one side??? Do you have a guess which side might be worth more? 
This does not mean that you have to play the suggested moves directly now, but you always realize that YOU have them at hand!

With my last move I just have to open another battlefield, which is very important for white. White is in fact reducing largescale areas of influence of Black. This must be done lightly. Hence I will try to end in every corner in sente  and approach the next one. Got it?]
;B[dn]
;W[dm]
C[That's correct reasoning AND only half of the truth! Then you could perhaps 1) kill the upper right white stones (later) and?!/or play Joseki moves Black C4 which could cut of the san-san invasion stone white C3. 
The outcome would still be beneficial to you in the lower left, because your side handicap stone D10 is perfectly placed then to use the influence which will be radiated by the black wall below (after all white must make some moves in the corner in order to live and YOU get the wall (and perhaps even sente?!).
Stronger players like influence and dispise small early territories.

Facing your strong influence then, the lonely white stone C6 must think carefully aout escaping. It is no problem to do this lightly - but does white make territory by escaping lightly?

Conclusion: You do not have to fear san-san (C3) invasions in a 9-stone handicap game, rather enjoy them as black. 

Once you dare to (and are able to) take sente you will have become a stronger player.]
;B[en]
;W[cq]
C[For the next move, try to recall "What is one principle in Go with a very high priority" which I emphasize very often?
Then do a move which does this - in good shape.

Remark: another move is also possible and follows the same principle, but globally.

Both moves are good & standard.
Cryptic?]
;B[co]
;W[dq]
C[Yes, great!
You did indeed the move which most players would give highest priority: C5. The principle I meant is: "Divide, separate, cut-off your partner's (opponent's) stones!". You fully grasped it.

The good shape is C5. This 'tiger-mouth' has no cutting points on your part and has a (relatively) firm grip on the two white stones above.

If you'd played on C4 instead, there are some variations to exploit black's bad shape. Also the white stones C6, D7 have more liberties and aji.

And - incredible - D3 was the other possibility I was thinking of. Strategically a very good decision too - building up a mojo on the right, allowing white some corner points on the left. After the usual continuation and a special tesuji (Chinese: shoujin; s.th. like good combination) Black gets very good influence in sente at and around E7 (later I will edit the SGF with variations of it). 

Then you continue with Black K6 and had a won game (theory: if it were an even game with equal strengths).

My last move is perhaps not the most correct (if we were playing an even game). 

That does not matter for you: again you must apply basic, fundamentalprinciples: separate or confine groups, block or capture stones. Any of 6 moves 
I am thinking of comply with this principle. Although perhaps only 2-4 are good on my level, I would be quite enchanté if you would play any of them.]
;B[cm]
;W[fq]
C[Right, I think your move is better.
Similar effect have E7 or B6.

On the right E3 or F3 were possible, whereby Black E3 gives white more tactical possibilities (e.g. hane W E2, counterhane B F2 and e.g. tesuji white C4! Threatening double atari on F3 or to connect a little bit via W B5. The keima black F3 on the hand confines white nicely and perhaps in sente.

Like this it is very difficult to win against black. 

White had to jump or would be perfectly sealed in and just live. With this jump, white looks into the right side, a little bit into the center and the stones can ply a role. 
Always avoid to be sealed in!

Now black has a very nice move PREPARING a double threat peeping the white stones or connecting to the black stone you will have played. 

If you do not know what I mean by peeping, pl. cf. here: http://senseis.xmp.net/?Peep

A selection of - mostly Japanese - terms is explained here on this site: http://www.dragongoserver.net/faq.php?read=t&cat=3

White can avoid your double-threat only by making one or two not-so-nice shape moves which white dislikes.

You will have created pressure on the white group and created some influence, perhaps even already territory on some side.

Where is this move?]
;B[ep]
;W[gq]
C[Well, that is not what I meant.
I said PREPARATION for a possible peep or connection to the right.

The threatening peep would be from below black E2, and if white prevented this by W E3, then black could connect with F2, IF the PREPARATORY move black H3 had been made. That was the move I was talking about.

>>> Black H3 <<<  

Ususally you do not play out the AJI (options, possibilities; here the peep E2) immediately (it would not work like this anyway). Rather you threaten with it. I think the same holds for Chess, where (Tartakower or Tarrasch?) is supposed to have  said: "A good threat is worth more than actually carrying it out". Think of a blackmailer, s/he can come back thousands of times blackmailing you with the same one threat on different occasions, but once the actual threat has been executed - it's all over! 

With my move now, I defended against the threat b E3, w E2, cut b F2; if i) w captures by w G2, b gives atari at D2, w takes the cutting stone at F1, b plays C2 and the two white stones cannot be saved anymore; or ii) w connects at D2, b captures wF3 by bG3 in a ladder (disconnecting white from the center AND the white corner could die if w does not make a gote move there).

Instead of my move wG2 defending against i) or ii), w could have also chosen B4 (pl. check it out), E3 or or G2 (and some others which are not so good). G2 gives some upward potential (like G3 now), whereas B4 destroys aji if you take a sone by B6 and B4 does not develop into the center.

BTW, against the present G3, there is still the nice aji of the nose tesuji http://senseis.xmp.net/?NoseTesuji
 threatening the same i) or ii) above.

You do not have to play this now!

This time I guided you in the wrong directions with my comments (because I got a move into the center, whereas your last move did not add so much). Hence, I will be quiter from now on. 
But I encourage you to ask questions.

You can also abbreviate the word "comment" to "c" in those brackets to include text into the SGF.]
;B[jq]
C[I am playing here to restrict your expansion along this edge. The AJI of the nose Tesuji that you were referring to, was this by playing H3?]
;W[mm]
C[Yes, it was H3.
It would have made necessary an answer from white in the lower left corner (in order not to be cut-off from the center, or lose the 2 stones CD3). 

You would have achieved something similar as with your GOOD move K3 now, but in SENTE for black! Meaning you'd got the time to make another move! The worth of such a move is difficult to estimate, but on average 10-15 points. (Your first 9 moves - handicap stones - are supposed to be worth 140 points, if two equal players are playing).

Now the lower right quadrant becomes frightening large for white - the upper left one too, but that's much more open.

Hence white MUST do something.
Many players stronger than you know the san-san (R3) invasion.
Black could/would not kill this corner, rather build a superb wall influence and the remainder of that quadrant would still be huge territory.

Hence I reduce first the outside with a light, non-committing move that should not die (and hope to be able to reduce later further, still from the inside (e.g. san-san R3) etc. :-)

In high handicap games, usually it goes this way.

I remember playing with a good friend and 5k, 15 9-H-games in a row, where my opening moves were 
N13, G7, G13, N7 + K14, O10 etc. whatever he did. Sometimes all the first 8 moves in the center. I only stopped, when he had won his first, the 15th game.

It was an interesting experience for us both. 

I told you before that you do not have to be afraid of white's san-san invasions - if they come too early! Because then you build up a more profitable wall tec.

Of course you must be aware of scooping-out your precious territory AFTER the outside has been settled. So, once the outside becomes worth less (i.e. there is a clearly living white group), take care that a white invasion would be doomed to death.

Among many other things, Go is about the Balance of many contradicting and inter-related factors.

Now, many different strategies are possible, I can only comment after your choice.

This is also because it's a 9H-game and if I have look at the board, I only see that black has a wonderful position everywhere. To compensate with that, black must commit many smaller and bigger mistakes. After all - the total handicap equals about 280 points (75% of the board)!]
;B[hq]
;W[np]
C[This move H3 is still a horrible one for white!

I have big problems defending against it in good shape, e.g. B4 or E3.I just have gote (opposite of sente) to not much more points.

The other one, G2 defends against it but looks awfully arkward. I will not play empty triangle here. If playing hane at i) H2 or ii) H4 white has i) not yet defended after black J2, or gets gote, and in ii) black could cut directly atG3 and separate white from the center.

However the global situation has changed now.Black doubled his efforts around HK3,4 and this is long not that effective as just having had played only H3.

How does white best utilize this? I think I give you your way in the lower left corner, you may cut off there something again in GOTE!

I think if white proceeds now in the right quadrant, then white gets a net profit from it, whereas black has played then 3 moves K3, H3 and a gote move in the lower left, for getting something there. (Actually I am wrong about the last gote move; the situation will become quite precariousif I abstain from there, you can seriously harrass me there; but in a 9H-game white must take calculated risks; I must give Black a chance to make mistakkes or sub-optimal moves).

This move N7-O4 is called O-geima (Jap. for great horsejump) and I hope I can transform it into good shape => living shape.]
;B[oq]
C[You seem to have sente every time!!

I am catching a train to Paris now, so all that remains for me to do is wish you a nice weekend!!]
;W[nq]
C[I envy you!

 ...seem to ...
I just take what I get!

There will come the time that view on the board becomes bigger, from local context to global vision.
Then your greed, or more positively expressed, eagerness to get other points as well, makes you evaluating the net profit relation of local losses with gains elsewhere. More often you will then tenuki (locally abstaining; not a PASS).
If done in a calculated way, your play will become dynamical.

Before you know it, you will realize my ideas, and develop counterplans. Do you remember the endgame sente/gote exercise which I showed you some months ago? The lesson there was, that you must try to (re-)gain the initiative. 
If both players want this, you get interesting games.
_____
I tell you my game plan:
Because you answered on the right, you will perhaps answer again there, now after I played.

Then I want to jump out to H5, and IF you do a combination and take my stones CD3 in the corner, I am happy to give them, if only I can get the K6 capping play (Jap. "boshi"). Then I had a target to attack and chase around etc.

Of course, in an even game my right group N7-O3,4 would be available for attacks too.

BTW, can an ogeima be cut?

... to Paris, hmmm]
;B[on]
;W[om]
C[Thanks, a normal weekend with the duties shoping, faire le menage and swimming on sunday with the family.

Your last move P6 threatens to cut my ogeima. I could defend by shape moves M4 or M3, but here I want to try something different.

If your sphere of influence on the right (it is not yet actual territory, immune to invasions) was not strengthened by the 3 stones QR9+Q10, your P6 could be considered giving white options, and a Q6 would be much stronger for that reason.

Anyway, if you'd cut now, we'd become tactical - if you defend I might have got a local advantage. However, as usual, white should take greatest care to leave the situation here first (get sente) in order to do necessary moves in other places on the board (is this a hint with a baseball bat?).]
;B[pm]
C[It seems to me Q7 is a shape move as well as a contact move attacking your P7. I want to try and get sente to play in the upper left quadrant or G/H5]
;W[oo]
C["... Q7 is a shape move as well" 
yes, other possibilities are:
Just black Q6 (only defensive follow-up for white, to protect the cut), or 

a try to cut-through immediately at black N5 (complicated follow-up)

 "as a contact move attacking your P7."
White is outnumbered by black stones, hence much weaker! 
The weaker party in a fight needs contact moves, NOT the stronger party.

By contact moves (attachments, hanes, double-hanes, crosscuts etc.), BOTH parties become stronger, but only one party needs the added strength, the other (already stronger party) gets overlapping, redundant strength in this kind of fight.

Hence, often you see one colour contacting very much and the other one is SEEMINGLY acting passively. This is however done for the reason above, in order not to help the weaker party reinforcing the weak stones/shape.

"I want to try and get sente to play in the upper left quadrant or G/H5"
Very good aim, indeed!
I want to play there too.

Already the simple fact, that you have A PLAN, makes you a stronger player. Also, it is a good plan.

Noe the question is, who of black and white can leave the situation first on the right?
It might include the option of accepting small(?), claculated local losses to move on to somewhere else. (like paying higher interests for doing new investments).]
;B[nn]
C[I am torn between O6 and Q5. I dont want to make you stronger by too many contact moves (as you have just explained to me), but I think both of these positions are where you would like to play. I like O6 better because I think it spits your attacking camp in two (or tries to) and allows me the possibility of linking up with k3/4. In addition to the peep at O7, I am pressurising the potential cutting point of O5.
Of course, I am expecting a sharp rebuttal of my analysis soon from you!!]
;W[po]
C[".. torn between O6 and Q5" O6 is an excellent move.
please notice, that your idea of Q5 would allow white for an atari at the very O6 you just played. Black would most probably connect and then white had connected his stones in sente and prevented the cut. This was whites dream sequence with the follow-up of playing on the left.

Of course you knew my plan and skillfully, actively agressively prevent this.

"I dont want to make you stronger by too many contact moves" good attitude!
"both of these positions O6 and Q5 are where you would like to play". Yes
Yes, O6 splits white in two.
"O6 ... allows me ... linking up with k3/4". Yes and k3/4 is strong already because they can link up to the center starpoint or to the left, esp. with the aji on the white left stones.

With regard to the "peep":
"peep at O7" Correction, the terminology would be more "peep at O6".
This "peep" is not at all important!
Any move could have many different labels. Of course one thinks of the more important ones first and "peep" did not occur to me at all. Why? Thinking of a peep would imply that with some probability white would like to connect there agains the cut at O7.

However, once these 2 stones NP7 are separated from the lower stones O3/4, they have no time to make so clumsy moves. Either they can be linked to some other forces, e.g. the Q12-group or they had to make or prepare eye shape, e.g. some jumps. A solid connection would only be suitable if there was sure territory to defend, which far from happening now.
Most probably these 2 stones are going simply to die (!), because a black move around P11 could be interpreted as sente move (to kill if ignored) the 5-stone Q12-group. 

Now, ask yourself: what is better, capturing one white stone P7 in Gote or capturing 2 stones NP7 + surrounding points in Sente? You see! That's why the concept of peep did not occur to me. 
"expecting a sharp rebuttal of my analysis" no, your analysis was right in many points and you came to a correct result.
"soon" I commented already very much several days ago, when suddenly the Viewer was refreshed ... I was upset and could not free the time to write again.

No rebuttal, but I must execute now some moves in the corner, because you should not cut me from the center AND get all the corner territory. However, if you end in Sente, the global result (that what Go is about: the global war, not just individual battles; the harmony between many mutually excusive factors) cannot be bad for you, because you could proceed as I hinted you here and there.]
;B[oi]
C[I have been eyeing up P11 for quite a while. I didnt think it was a big enough stategic move, but if I can keep sente, this move has the added benefit of staking out a nice moyo towards the centre. I still want to play in the upper left quadrant and an enclosing move involving the lower left corner and my hk3k4 group.]
;W[nf]
C["I have been eyeing up P11 for quite a while.”
Even before I made my commentary? Wow!

“big enough strategic move”: Moves in general become worth more, the more goals they serve and functions they have. Here you attack the white top right group (already by sealing it off from the center) and stones in the NP7 area. Despite it is a big move, you must also have considered playing first move like black R4 or R5 in the corner  in order to get some life there AND/or  N5 or M5 for separating. The capital AND is for the case that you (might) end up in sente when starting with R4 or R5. As in normal life, a vision or here dreamscenario is quite important. Next to talent, environment, motivation and discipline I consider it quite important for achieving goals (circular reasoning: the vision would encompass the goal).

Even if it does not realize due to your partner’s/opponent’s moves, your own calculation errors or simply a shift in your evaluation (hence goal/vision), your dreamscenario could be:
I take sente with R4 or R5, then with N5 or M5, then I take sente with P11 (the move you just played), then … and in the end you are dreaming of winning with 100 points.

This is not a bad dream at all, even if we all make errors and/or the partner plays different moves. Everone should know what to do with the his/her next move.

I must send you the rest of my commentary by my SGF, id dit not fit in on Dragongoserver.]
;B[lf]
C[I liked M14 because it still closes your group from the centre and is less risky than n14. Also it aims a towards the upper left quadrant. I was thinking about N 14 but thought you might have better counterchances after you crossed with N13, or after 012,P12,N13. Anyway, maybe I should have been more aggressive, I dont know.]
;W[pn]
C["... M14 is less risky than N14." No, that is not true. M14 gives white here simply more leeway (levy?) than N14. Although, I have to add that sometimes this more distant move M14 is the stronger attacking move (because it is not a contact move and does therefore not strengthen white).

"I was thinking about N14 but thought you might have better counterchances after you crossed with N13 ..." See commentary above.

"Also it aims a towards the upper left quadrant." By enclosing white, N14 would aim there too.

"black N14, white 012,P12,N13..." this atari would simply be answered by black P13 connection and white's two stones O12 and N13 have few liberties, almost no function and there is the gap at P14. Very bad combination for white.

"Anyway, maybe I should have been more aggressive ..." 
By playing well, you are agressive enough.

The move I am playing now results from my un-ability to decide between S15, N13 (I think white can handle the problem at P14) above. I do not want to play a move P13 because it does not add so much to the security of the white group (black S15 is still a threatening move) as it destroys at the outside. Black would play O12 and had sealed of that part of the center nicely.

On the other hand I do not know exactly how to play at the bottom. The outcome at the bottom is influencing my decisions on the top and vice versa. At the same time I cannot tenuki (refrain from playing in the local position) - can I? - and wait for you to decide.
I cannot find a, the yosu-miru move (probe, http://senseis.xmp.net/?Yosumiru) which forces you to decide on the position and I play then the moves which fit it best - if there is such a move here. Well-planned tenuki and yosumiru are high level concepts of better players.
It seems I have not yet reached this level. Herewith I just give you some food for thoughts in coming games.

The move I am playing now is not as strong as R4, R5 or even S5 vs. the corner.
Hence, your corner stones have now a stronger chance of survival, making it more difficult for my stones O3/4-Q5 to live if you cut me off from the center. Why do I play it then? Because I think I have this way more possibilities against your stones OP6 (and you can cut me less easily). Go is a difficult game.]
;B[mo]
C[I like N5 because it takes a point that you want and also allows the threatened OP 6 group a way to escapes while possibly threatening the left side of your O3/4 group. I was toying with the idea of S15 too. Maybe I should have played that first?
I am meeting a friend at lunchtime, so I will be late (45mins or so) for GO today. See you there all the same!]
;W[lo]
C[Perhaps not objectively the best move (can be detrimental, if you move in a certain way), but it leaves/creates some tactical options, if you respond in otherwise.

At some point I will have to return to the corner (for controlling the two black stones).]
;B[mp]
;W[qp]
C[The last black move was a simple good move, separating white stones WHILE increasing liberties.
Black did trap into any complicated cutting business (decreasing liberties and giving white  a chance).

Eventually, white must come back and take care of the corner - if black was to live there, white's stones might not survive.]
;B[nm]
;W[bn]
C[Black's last move seems redundant, because concerned with black's safety, you had either this move or M34 etc. to connect & safe your cutting stones.

Instead, black could have made an extension from the upper left 4-4-point, harrass the white upper right group, e.g. by S15, do some cutting exercises around E3 etc.

Instead of the white move now, white also could try to prevent the above mentioned moves and play there himself.]
;B[dl]
C[I didnt realise that you would tenuki on my last move! I lost Sente. Silly me!
I was thinking of sacrificing my C7 stone for good outside shape, but I thought, why not use it in the ladder on your D7 first?]
;W[cf]
C["tenuki on my last move.." - White didn't know a good local continuation!
                                           "I lost Sente" - Yes
"Silly me" - No, inexperienced.
                                           "was thinking of sacrificing my C7 stone for good outside shape"
- black can get good outside shape also by not sacrificing C7.
"why not use it in the ladder on ... D7...?" 
 You could have played black B5 instead, it captures BC6 and also looks into the white corner!]
;B[df]
C[Again the attach and extend joseki!!]
;W[dg]
;B[ef]
;W[cd]
C[Instead of the attach-and-extend joseki, black is in a high handicap game (6-9 stones with the side hoshis) always well of with the kosumi-stuke joseki (starting 4 moves before).

\[http://senseis.xmp.net/?KosumitsukeJoseki\]]
;B[gd]
C[I wasnt too sure whether to attack you in the corner or stake out some side territory on the top of the board. I decided to do the latter]
;W[dc]
C[You could have staked out territory by attacking my (weak) group - you still can!

My last move is reckless - punish White.

To create so many cutting points - I only do it for your as an exercise.]
;B[ec]
C[I accept your invitation!!]
;W[de]
C[I meant cutting at C17 !
That would cause big trouble for both.

Now, black G16 looks overconcentrated.]
;B[ed]
;W[db]
C[Please consider, for the future: what are the consequences of a Black cut at C13 for White?

Can White capture the cutting stone(s) C13? If not, what could white do? 

What would then happen to the white cutting stone D13?]
;B[cg]
;W[ch]
C[First of all: whow! I'm impressed by your deep analysis.

It goes far beyond that of an 18th kyu. You must have improved in the meantime.

"I guess you can couteract this with C12" - Right.
"and after I extend, you will play elsewhere with Sente." - NO! To give atari on the black cutting stone from above induces the black stretching move (Jap. = "nobi"). If white then abstains from that area, the corner is weakened.If, on the other hand, white really wanted to sacrifice the very important cutting stone D13, then she would do so from below (atari B13) and make territory. 

"Your D13 is a source of weakness which can be exploited by black." - That's the right spirit! In a handicap game - attack!

"I'm not sure where you could play next" - that's the skill, nibbling around here and there
"...as things are not looking great for you." - especially in the center!

"I think maybe a jump to G5 trying to separate my h-k group from the lower left corner."
- you are already somewhat connected to the black N4-group.
If I wanted to separate you (after G5, K6 etc.) with M4, white would get liberty problems with M4 and/or the corner group.
Hence, that move G5 is a good one, but not threatening black groups. Furthermore I told you as earlier comment, that there was some (complicated) black cutting action starting with E3, which lets black heavily compensate.

"THe only thing is that I might make it to the centre." - YOU ARE in the centre!

"Alternatively you could make a dogs head pattern with M5,N7 and L7." - Nice shape! Did you learn that in our course?

"Other moves such as E18 dont seem that strategic and serve only to slightly limit my territory." Very correct! (this "slightly" is only for the moment, later this move gains hugely relative value.]
;B[bg]
C[Well I have been playing quite a few fast games on the KGS which I think has boosted my game, but the greatest credit goes to you and the material you have prepared for us each week. I just read the stuff and some of it stuck in my mind!!

I thought that by playing B12 you would allow me to extend B14 and followed by B15. Your D13 stone is vulerable and would allow me make wall-building moves for free.]
;W[eh]
C[... fast games on the KGS ..." That means that I can see them , right?
"greatest credit goes to you"
Thank you very much! The biggest credit actually goes to your own motivation.
The greatest compliment for me is, if all of you have a good progress in skill.
My dream would be, that someone of becomes European 4-5 dan and teaches me!

"the material you have prepared for us each week." That takes some time , indeed.
                                   "... thought that by playing B12 you would allow me to extend B14" correct (atari on Wc14)
" followed by B15." No, that would mean a flower-ko for you. (You lose few, for me much would be at stake)
"Your D13 stone is vulerable and would allow me make wall-building moves for free."

Yes, if you simply were cutting at D12 (after Wb12, Bb14, Wc15), you would simply win the semeai (close combat) by Bc11.

That's why I protect D12 now.
I hope to capture bc12 + being in the center.

If White was defending D12 by e.g. D11, black could squeeze white and get an outside wall.]
;B[eg]
C[I want to play at f12]
;W[dh]
C[If Black wanted to play f12, he could have done so without this atari.

Remember the proverb "Atari, atari - vulgar play".

You can remember it differently: Mosta ataris, where you cannot capture, or do not expect to succeed or be allowed to capture - are bad. They just strengthen the opponent.

This atari here for example changes a little bit the situation around b12/13/14. Now White could capture the 2 black stones by coming from behind (b14) and is not anymore dependent on the situation around bc8 (if black had crawled to there). Small difference - nevertheless. (You still have the atari at b14, but it is not necessary to play it).]
;B[fh]
C[I understand what you mean by the ataris, but I also wanted to stengthen my wall by playing that move!]
;W[fi]
C[If you fully understand what I mean, then you would not have played it!

The point is that you could play that atari at any time, it is so important for me to answer, that I simply have to!
Sometimes it happens that 2 groups of stones are then in atari, mines and yours.
As long as my stones in atari are more important than yours, you do not have to (= must not) give the atari in advance.

You then have saved ko threats, usually/very often also your own liberties, and you might go a totally different course in the future => ruined aji (options).

Often you would like to give the aji later from another side or peep instead etc. 

"wanted to stengthen my wall" as I say, it had the same strength without that atari.                  

The principle of flexibility (from Dieter Verhofstadt on Sensei's) 

Go is a game of complete information, but it is far from being solved. Some board positions, however, are already solvable by the mind (killing large groups, endgame). In these situations, the player who sees a sequence giving him undisputed victory, will play out this sequence. This can be called "settling the shape". 

If settling the shape does NOT give a definite advantage, then it gives more information to both players. In particular, when the shape is settled with one move, the opponent is the first to adopt a way of playing that takes the settled shape into account. 

Therefor, as long as it is unclear who is favoured by the board position, both players will keep their options open as much as possible. This applies also to part of the board. 

(i) Preserve flexibility as long as the position is unclear 
(ii) Settle the shape when the position favours you 

To my last move:
it is not the best one. Because of the threat of cut E11, I should have played the proper move (jap. = honte) B12 or 14. Then you would simply play F11 to have a safe center (better than Be11). White F11 is too greedy, it can be punished (the immediate cut is not the answer, because then white still can play A12).
                         
Why is white then playing F11?
1. This is a teaching game. I want to give you the opportunity to see white's mistake and punish them. 
So I make some objective mistake on purpose.
Obviously it is much harder for me to discover my real mistakes & wrong concepts, otherwise I would play better.
2. Some players might think F11 is the more active approach with white getting into the center. Some might see that white can end up eyeless in black's ocean. Some see that black can err when cutting, therewith getting only a small advantage.

This last way of playing is called hamete (trick move) when well known and usually in the opening. In the middle game, not in a standard situation it is called "overplay".

To be complete some "overplays" are not such and the opponent simply has the correct feeling that s/he is outplayed.]
;B[bh]
C[I think it is a good idea to see if I can spot how to exploit the deliberate mistakes you are making. I dont see any harm in this move, because at least it forces you to react to it otherwise your group is in danger of dying.]
;W[ci]
C[Good move! White cannot hane (bend around) because of liberty problems. 
Your group has now 4 liberties and virtually 5, because you can atari ( agood one) at b14 and gain 1 liberty. I must answer, because my C 14 is a cutting stone, hence ultra-important.

How many liberties does white have? Does white have eye shape, even if increasig liberties? Can white stop black?

Posing those questions is almost answering them.]
;B[bf]
;W[ce]
C[Right, it even has influence on the aji in the corner.]
;B[ei]
C[the liberties are being reduced and I am cutting your group off from its escape route.]
;W[cj]
C[You made a correct choice.

"... liberties are being reduced" Yes, the one's of your cutting stone e11 too!

White can use this for saving his stones (I objectively hope).

".. cutting your group off from its escape route." Yes, from the center.

Here are my previous thoughts:
At first I thought that Black better should have pushed on the b-line first (B11, B10). Thereby black had collected liberties and threatened with every move to hne (bend around white) on the 3rd line.

If white always answers (twice), black has to remove the aji of white D7 by capturing at E7.

However, White can then win the semeai, because w is not yet cut at E11 , hence has many liberties, whereas black has only 7 with a row of 5 stones on the 2nd line (too short for making eyes).

This would have been a desaster for Black.

Playing this way only would make sense if black could connect underneath to C7 (with Bb11, wc10, Bb10, Wc9, kosumi Bb8, Wc8 atari, Bb7 and white pulls out the cutting stone with e7.

This is objectively, relatively complicated (quite for you) and I think that white would be better of:

Black will not be able to capture the cutting stones DE8 AND connect underneath.
If Black connects underneath and captures white's 2 stones bc6 that's only the 2nd row (too low). White would capture move 44 (D8) meaning life in Black's center and be happy. 
                    
Conclusion again: correct to give up your stones b12-14 and preserve your center.]
;B[fj]
C[I wasnt too sure about my 2nd row group of 4 B stones so I thought I would just cut you off before deciding what to do. I didnt go into the same in depth analysis as you but am relieved that it was the good decision! Here I was torn between this move and G11. I like the latter because it stakes out the centre a little better however there would be a lot of cutting points. The move I played momentarily protects me from E10 thereby indirectly threatening your group of 6 stones.]
;W[bm]
C[I wanted to shout "Atari, atari vulgar play!", but your move actually works, because I have no time to pull out at G11. Black C9 would capture white stones before the counter against black's stones e13/14 would work. 

Now I cry myself, if I give atari at Wb7, throwing any aji of the cutting stone D7 away.

"Here I was torn between this move and G11." Bg11 would be a horrible move, only strengthening white.

"I like ...(G11) because it stakes out the centre a little better however" the centre is already there! 
"... there would be a lot of cutting points." which would be detrimental to a big center!]
;B[cl]
C[I think D7 is dead anyway so I'd prefer to join my C7 and D8 stones. Also, C8 is well placed near the head of your group. I envisage that you play B8 next and then try to link up with your 6 stone group.]
;W[bl]
C[I got quite a shock, when I saw your move.

It would have been good style to simply take D7 by E7. Hence I overlooked your move and its implicated danger. Seeing your move, I thought that I am doomed with a lack of liberties if I do my move and you hane at B9.
Luckily it still works ( by 1 liberty)]
;B[bo]
C[A quiet move]
;W[gi]
C[This nobi (stretch/extension) avoids that Black can make a ponuki - all aji would be gone.
Now these stones have 3 liberties and White can use them for a longer time - even when sacrificing them.

That's why one usually has strong doubts about the move preceeding it (the black atari F10).

Go is a game with few rules, many inter-related heuristics and exceptions.
Hence it might have been a good move here - to close of the center (as you indicated).

But Black sh/could have used the last move to make a ponuki and make the center aji-free and ultra-strong!

Blocking at b5 has no influence anymore on the small fight on the bc6-14 lines - that's already settled.
Luring into the corner is comparatively small at this time. White must penetrate the center.

Repeated conclusion: Black should have used twice the opportunity to capture cutting stones (D7, E11) for good to remove all aji.]
;B[ck]
C[I should have made the ponuki alright. I was tempted by your side group - maybe even obsessed about it. I should have played for the centre instead of focussing too much on the left side. I thought you would have to react to my previous move, enabling me to ponuki later. I think now you must reply to this, otherwise its curtains for your left side!]
;W[bk]
C["...maybe even obsessed" It's ok to be obsessed - by good moves!

"...thought you would have to react to my previous move .." Exacter Reading is an important cause for better play - next to the simple good old style/shape.

".. think now you must reply to this..." Right, but it doesn't make it a good move. It has the features of an atari:
- it is necessary to react (sente)
- it settles a situation
- it takes away aji/possibility  to play otherwise later (e.g. hane B9)
- it has no drawback for white if you play it
- it HAS a drawback for Black:
the liberties are reduced (aji for white is created; I am already actively planning)
- Black does not lose an opportunity if he does not play there, because white cannot play something useful there herself.

- A simple play at Bd9 would have had the same effect as this crude move C9 (empty triangle) because white had to react, otherwise hane Bb9 is threatening to split (as white would lose her stones if she intercepted then with Wc9 => Bb10! capture).
        
So, objectively there are enough reasons why this move is superfluous & bad.
Even if you cannot see yet all the tactical implications why it is BAD, you surely can RECOGNIZE the TYPE of move (empty triangle, takes own liberty, is a forcing move, causes white to  connect safely) - AND THEN REFRAIN FROM PLAYING IT!

Sorry for the shouting, but it will make you at least 2 stones stronger if you follow my/this advice!]
;B[em]
C[Sente goes to white....
I could/should have got more out the previous few moves. I thought I could kill your side group.]
;W[ek]
C[For killing you must have a clear picture of the sequence(s) in your mind. Anticipating the strongest answers is not easy.
Usually one misses a lot. Therefore it advisable to be prudent.

Reenforcing oneself first is a very strong attacking weapon. Leaving no weaknesses behind gives a good feeling. It avoids "amarigatachi" (http://senseis.xmp.net/?Amarigatachi)]
;B[ej]
C[I knew you would play E9!!]
;W[ee]
;B[gg]
C[My options are not great here. I cant really play F13 because it will lead to bad shape, but also this move will allow you to force me to make empty triangles. G12 and G14 are also unplayable as you will be able to trap my group. I cannot afford to lose my F12 stone as that will give your side group a definite eye + access to the centre.]
;W[gj]
C[Your move is stylish and very good shape!
"... cant really play F13 because it will lead to bad shape..." 

YES, but the governing principle is the effectiveness of the moves, hence, even if an empty triangle is the epitome of bad shape (and usually inefficient) - an empty triangle can be played without moral worries once it solves a particular problem in a specific game.
(No shame on you, when killing groups with an empty triangle in nakade shapes).

I would subsume this excursion as Axiomatic DOGMATISM vs. effective principles.

Furthermore you are right, empty triangle on F13 has a weak spot on G14, setting up geta (net) threats (after some preparatory work with white G11/10 to gain some liberties).

"G12 and G14 are also unplayable ..." 
Both ARE playable (they are free points), but it is to decide which one is best.
G12: Very often in close in-fighting, there are sharp moves very dangerous for both. G12 also takes a liberty af the 2 white stones FG11 away.

Your played G13 seems best, because it seems to protect best the cutting stone F12. No need then to capture white by taking liberties away (black G12), rather you swallow white.

Very correct:
"cannot afford to lose my F12 stone as that will give your side group a definite eye + access to the centre."

White would like to capture the single, pivotalcutting stone F12! It is not the 3 stones DE14/13 which are important (as the semeai on the edge (b-line) will be won until now by white (this may change if white loses the F15-liberty: then Bc17 starts a cutting action which gains one liberty by squeezing white, the pushing at Bb11 and the liberty count is 6-6 with black to move. \[Psssst: This message destroys itself after being read ...Forget this now!\]).]
;B[gk]
C[I prefer G9 to F9 because it takes away a liberty from your group of three stones, it also encloses the E9 stone. You will be able to force an atari of my G9 but the centre K10 stone then comes into play by supporting any group formed by my escaping G9. I was also tempted to play F15 but I think you would have major counterplay with your group of three stones and E9, so I opted for G9.]
;W[hk]
C[Good thoughts!
But how could I atari your G9?
(if you make good shape?)]
;B[gl]
C[I thought you could play Wf9, forcing Bc9 and then Wg8, but I think that is bad for you after I extend with Bh9.]
;W[hg]
C[1) Wg8, forcing you to a good move (stretching) would be horrible.
2) Wf9 could have also replied by Bf8, W has then only 2 liberties and can't do anything.]
;B[gf]
C[I obliged to play g14 here.]
;W[gh]
C["obliged to play g14 here."

Not really, I also thought that the blunt Bg12 might be possible for you , ruining my shape.
After all White is not interested in the stones DE13/14, but rather wants his center stones connected or with living shape.

Because I pondered about this, in a real game I (white) had given the atari first, then played my move H13 - the ending position being as now.

I wanted to see whether you come up with that move.
I wanted to avoid the atari, you wanted to avoid something empty-triangle looking.]
;B[fg]
;W[ii]
C[shape move for eyes (not a single eye yet!)

I honestly don't know what to expect (in the center).]
;B[ij]
C[Lets see if I can prevent you from making eyes!]
;W[hj]
C["prevent eyes!" 
The move looks quite blunt - but in this type of open  L&D-problems it is difficult to advise best moves]
;B[ih]
;W[ji]
C[Your move is good!
It is very dangerous for white!]
;B[ki]
C[I think I would like to stop you spreading along the 11 row. Also, I feel there are still escape routes fo my j12.]
;W[kj]
C[Black offers a cutting point, where white just cuts for creating aji.

Black should have calmy extendet at the same point (L10). 

"would like to stop you spreading along the 11 row." Rather stop me getting one or two eyes.
"escape routes for my j12"
I 'll threaten to capture it, thereby creating more double threat-aji's.

If white does not succeed in the center, white is doomed]
;B[kk]
C[Are you making the aji because you are sure what you are doing or hoping that something will come out of it?]
;W[lj]
C[" .. sure .. OR .. hoping ?"

IMO it is not a contradiction to say "both".

I estimate the center issue decisive, therefore I hope that I succeed.

and

I am relatively sure that I make good moves (which eventually will lead to something).

I)  In a 9-stone H-game, White has to fight & struggle for a long time in & against an overwhelming influence.
White looks forward, stays positive and trys to play good moves, bit by bit. Usually then an endgame starts where still 10-40 points have to be made up.
With some lost sentes on black's part, an overlooked L&D-implication, some partisans escaping, white can make up in 50% of the time.

In the middle (stage of the) game, where we are now, small differences can have big effects.

E.g. your last move again was ATARI (and a bad one): white is strengthened, black still has the K9 point to defend => white got strengthened in SENTE. 
It will go on like this. If I succeed in teaching you avoiding these ataris (only this!), you gain at LEAST 2 stones in strength! 

=> With every atari you want to make, ask yourself 
"1) What is the/my purpose of it? 
2) What are the disadvantages of it? 
...2a) Do I strengthen the other party
...2b) Do I weaken myself somewhere else (or in the atari region)
...2c) Does the other have to respond?
COULD I LOSE SENTE?
...2d) Where would the other like to play
...2e) Where would I like to play AFTER or INSTEAD of the atari?
3) Can I also give the atari later?
    
II) The more you play on even, the more the gap between hope and being convinced of the outcome must and will vanish.]
;B[jh]
C[I know what you are going to say. I shouldnt be giving Atari, but I have thought about this and here are my reasons:
1.It strenghtens my j12 stone
2. Theatens your jk stones forcing you to join them to the bigger group, therby reducing your liberties.
3. This move threatens either h12 or j14 after having played bJ8.

I am not afraid of a ladder on L11 as I have co-operating stones at m14 and o13.]
;W[hi]
C[The atari before had the detrimental impact, tha dammage is most probably done.

This atari now could be ok.]
;B[il]
C[I hope to contain your group here.]
;W[kh]
C[It is a stylish move.
You could have played it - or once as an exception the empty triangle k9 - instead of the atari L9 five moves before.

Now it's pay-back time.
White can see now already that at least one black stone can be captured. Even if this will not create an immediate eye, it surely enhances possibilities (further aji).

The harder black resists - usually the better for white.

Examine what you can lose and decide what to give.

Right now we are playing the ShapeGame (http://senseis.xmp.net/?ShapeGame) as yesterday in the club.]
;B[kg]
C[I see what you mean. My L11 stone is too weak and your attack on it threatens my JK12 group with capture by wK13. I hope to stop you getting an eye by playing L13 which also supports my JK12 group.]
;W[li]
C[Getting no eye, rather a liberty more, hoping to exploit black's weaknesses.]
;B[lh]
C[I am going to play this and after you fill, I will extend to n12]
;W[mh]
C["...will extend to n12"
You should not give clues away.

White could play in several other ways. I do not which one is the best, I just try to keep the game interesting, hence I do NOT connect (indpendent of whether it's good or bad)]
;B[ni]
C[I shouldnt give hints, but there are no lies in GO, the truth is on the GO ban so it shouldnt make a difference to you!!]
;W[he]
C[White would be virtually alive, when allowed to capture Bn12! Thereafter, the only aim to remain would be to make some points in Black's upper moyo, resp. to destroy it.
That is far to easy! Especially in a 9H-game.
(Why black o11? This group is safely linked to the lower part of the board by Bo6 etc.)

Therefore I do another move - allowing you to take back your move is not an option on this server. (You should have captured by L11 (limits white's liberties to 3+ko on the left and threatens to cut-off the 3 stones) - and evenly important, perhaps not given this atari(!) m12 in first place!)

Because this is a teaching game , I want to create as many interesting positions as possible.
Hence, my next move is not a pass, or a defensive move (e.g. e3 or b3) rather this peep h15.

It is very dangerous - for both sides!
Remember, I told you already, that taking away white's liberty at f15 let's black win a semeai with the 4 b13-stones on the left against the white b6-c12 group. On the other hand, an f15 move would make black very very vulnerable too.
What does black do? The push Black h14 takes away a liberty of black himself too. How to answer?

After that I will have to make a pass in order to allow you to take back this ko at L11.]
;B[if]
C[It was a choice between Bj14 or Bg15 for me. I like this one as it gives a route to the upper centre for my threatened d-g group, reinforces my j-m constellation and encircles your centre group. The reason I played my previous move was to give me a better chance of creating an eyespace in my right group as I thought there might be a risk of it being cut off from the main bunch. I now wish I had played Bl11 instead.]
;W[hf]
C[Bg15 had been a simple, solid move, increasing the liberties of that group without cutting points.

Actually, the game would is over now, if white can capture at m13. White would live easily and wrapping up endgame points is then only a routine job. (I have to pass once*, in order to allow you to capture at L11 and remove your cutting point at k13. Hereby you also learn that your last move j14, inspite usually good shape for making eyes and protecting cutting points, is here not effective: after all, it is superfluous after the cutting point at k13 ceases to exist.)

White could then exploit cutting points at k13 or connect around o12 for living.
BLACK SHOULD have captured at L11 and even better - NEVER GIVEN that ATARI preceeding it!
In this game, bad ataris occured several times. I hope that you have learnt this proverb by now "Atari, atari - vulgar play". 

Now back to your choices on the left side: 
simply connecting at g15 is now the only option (as f15 would lead to being captured in damezumari).
Therafter white would like to push further at h16 to separate and harrass this black e-g14 group in sente, thereby creating option for white's center group.
Although - you had then a (very) clever answer to that 
push h16. (hint: white would lose sente)

Now: after you connect at g15, White will pass and black must recapture at L11.

*Rob van Zeijst (7 dan) is quoted "In a 9-stone handicap game white has 9 additional liberties in semeais about big groups". This would mean that black does not exploit situations to the full extent, incurring a loss of about 1 fighting liberty per rank s/he is weaker. In our example, this would result in about 20 liberties or several pass moves.]
;B[ge]
C[Thanks for the free move!]
;W[]
C[It's necessary, otherwise the game is virtually over!]
;B[ki]
C[Ok now, lets see what happens next!!]
;W[hd]
C[The rules do not permit for immedeatley re-capturing the stone.
We do play a ko!]
;B[fe]
C[I have racked my brains to find out this "magic" move of mine to hand me sente. I came up with two possibilites: the move I played (I think you cannot afford to take my l11 stone now) or Bh12. The only thing is, after the latter move, you would simply have captured the l11 stone.]
;W[cc]
C[Your quest for what I called the "magic" move was fruitful: 
It makes one eye for your black group in sente, hence limits white's attack possibilities.

Now , still be careful with that group, remember the reversed Clausewitz "Defense is the best attack"!  
(don't rush the attack, resp. defend)]
;B[hc]
C[I am really unsure what I must do here. You have told me that I must not let you take l11, but I risk my group with the one eye if I dont play something there immediately. So I guess I must play for Ko threats.]
;W[kh]
C["must not let you take l11.." right
"but I risk my group with the one eye if I dont play something there immediately." Right, white has laid eyes (anti-metaphor) on the attachment g17, in order to take away the 2nd eye of the black group, catch it and thereby gaining life for the Center group!

"play for Ko threats" Yes/no, and White cannot allow to pass now.
You could also simply connect at m13, acknowledging the earlier mistake and try to fight on from there.
You do have ko threats, several (5) on the left (big) and several (2? each) for the remaining white groups.

White has to use internal ko threats.
Black should also always start with internal ko threats.
However here, everything might become irrelevant, once white has captured through at m13 (= no internal ko-threats for black).

While fighting ko, the stakes here will become higher, and at some point even a side group threatened by black might be smaller in size/value.

It is up to you what to chose.
Playing ko adds more dimensions to the game, usually white profits from it.]
;B[be]
C[I dont quite understand the phrase "internal Ko threat", but the clearest one to me seems to be the stone I just played. The question is, which is more valuable for you, the side group or continuing to kill in the centre?]
;W[bi]
C[Please check out what internal or local ko threats are at:

http://senseis.xmp.net/?InternalKoThreat and 
http://senseis.xmp.net/?LossMakingThreats
 all refernced by
http://senseis.xmp.net/?KoThreat

Your 2nd question: off course I need both, center and side!]
;B[ki]
;W[fk]
C[This is an internal ko threat. An internal ko threat is directly linked to the group in question.
Its underlying idea is, that negating it would make no (or less) sense, because then the group in question would be safe and the ko is supposed to be smaller. Of course trade-offs are always possible, especially when one evaluates differently (beauty lies in the eye of the beholder), or one has wrongly estimated the number or values of ko threats or shifts game plans etc.

Here, other, external ko threats would be too small (for white).]
;B[el]
C[I must respond to it, so I do. I read up on the websites you sent me about internal Ko threats. It is also a local Ko threat. Anyway, I see what you mean!]
;W[kh]
;B[ig]
;W[lg]
C[Now (after black protects his cutting point k13)
white cannot ignore it and pass again, White has to capture now (Black should have connected at m13 himself or captured at l11 before! This was the whole point of discussion during the last moves)

Black has two problems now:
the cut at L14 and white's push through at o12.

Can black do s.th. about them and protect them both?
(sometimes atari is good - it could lead to another ko)]
;B[mg]
C[I am going to listen to you last hint and assume that this was the atari leading to KO. I guess you cannot immediately play Wl14, but I dont like the look of things for black.]
;W[kf]
C[" hint, ..assume ... atari leading to KO." correct

" (White) .. cannot immediately play Wl14 .."
White even has to.
If bwhite connects, this leads to nothing more than some liberties, but not eyes, because black will protect the cutting point at L14 and white has not many real options.

Esp. in a handicap game the following "proverb" holds: "If you don't dare to play ko, don't play Go".
Objectively, White might get 2 moves for free, if black at some stage might either fill at m13, capture at L11 or chicken-out with a fill-in at k13.
The last-move even would give White further follow-ups.

Hence, white might get 2 moves in the surrounding fights and has some chances/options]
;B[lh]
C[Well I am not going to chicken out of Bm12 anyway.]
;W[gc]
C["chicken out ..." of/from? k13; perhaps later?]
;B[gb]
;W[lg]
C[Timel later ... to chicken out?]
;B[bd]
C[Such a choice of moves, I didnt know what to play in the end.]
;W[bc]
C[Black's last move threatens the corner*, and , if this was to be captured the lower left side group. Good ko threat.

*Because you connected some time ago at e8 instead of d9, black cannot give atari at d11 (would be auto-atari) hence every liberty of the black b-line group has less threat to the white b-line group than before (every liberty black gained threatened to capture the white group).]
;B[lh]
C[back we go to Ko!]
;W[fc]
C[Go4ko! 
of course, threat-as-threat-can

<li><a href="http://gobase.org/studying/articles/">Articles on GoBase</a>

If you want to read some serious stuff on Ko, then read these articles:

<li><a href="http://gobase.org/studying/articles/matthews/ko/">Charles' Matthews articles on Ko</a>

They comprised several eye openers for me (European 3-dan).

Just trying to reference the samelink in another way:


<li>Charles' Matthews articles on Ko: <http://gobase.org/studying/articles/matthews/ko/>]
;B[fb]
;W[lg]
C[The last comment included 2 <li>< font color=red>clickable</font> links! 
They had the same coloour blue , though.]
;B[eb]
C[I am not sure if this is a real Ko threat, but it does remove a liberty from your upper left corner group.]
;W[mf]
C[1) First of all: I would not usually play the over-agressive move of n14, rather resolve now the ko by capturing BL13 with Wk13. For teaching reasons, I want to give you more chances to play ko threats and possibly punish white for his over-ambition of putting the stakes higher in this ko  (if black captures & wins this ko, then Wl+n14 become meaningless and the white group might die)

2) It is not a valid ko threat for our important ko.

YES, it lowers the effective liberties of the white group.
NO, it does not endanger that group:
Black could reduce that group to a bulky five with 8 internal liberties (more than the "dame" you count) plus external ones, minus 2 liberties for black stones inside => 8-2+1 = at least 6 liberties.

The black group on the b-line has only 5 liberties! Hence, white will not die.

3) More information on eyes, Nakade-shapes and their liberties can be found on: (please click on the links below, I still have to experiment a bit)

<li>Liberty counting Tables: <http://ourworld.compuserve.com/homepages/SGBailey/seki_tbl.htm>

<li><a href="http://ourworld.compuserve.com/homepages/SGBailey/seki_tbl.htm">Liberty counting Tables</a>

<li><a href="http://ourworld.compuserve.com/homepages/SGBailey/seki_tbl.htm">Liberty counting Tables<font color=red>font</font></a>

<li><a href="http://senseis.xmp.net/?CountingLibertiesAndWinningCapturingRaces">Counting Liberties and Winning Capturing Races </a>

We do have "Richard Bozulich's Second book of Go" in our library, where Steve Bailey's Liberty Counting Tables are very well taught by many examples (although the table itself is missing!)

4) A better, at least a real ko threat would have been Ba11, because  with another move , black can reduce white's liberties to 4, while black himself has 5 liberties.

Black's b-line group would be revived, the white corner could be killde in the future.

We are talking about 2x(6B stones + 12W stones) + 13 territory = 49 points + the option of the corner ( 2x9W + 8T = 26 points; hence a maximum of 75 points (but with 2 moves, hence 49 points + a threat on further 26 points, averaged 602 points; a rough guess)

Now you re-take the ko, what will happen?]
;B[lh]
;W[ic]
;B[ki]
;W[hb]
C[Now this black group on the f12-18 line has only one eye, but 4 liberties.

White's group f-k11 can a) be cut at h12 and has then 2 liberties + the ko about three more liberties (=5).
Because the ko at WL12 threatens to capture further with double-atari at Wm13, white stands good in this fight.
Otherwise (if white had no follow-up), black would simply fill a liberty at m9 after white captured L12 and the liberty race would be 4:4 with black's sente after white had filled at WL11; but that's not the case here).

b) If black only fills the ko at 
L12, white connects at h12 , has 8 liberties and lives by capturing the f12-18 group.

I do not see a 3rd option.

Hence, it seems best for black to cut at h12, white plays the ko at L12 and black looks for a big ko threat (Ba11?, Br3?, Bs15?; Be3 is small) which white ignores(?) because the fight about the middle group is of utmost importance.]
;B[hh]
C[I so want to play Bd19, but I think that cutting your group is more important.]
;W[kh]
C[Bd19, or any other move in the corner should not work (because of lack of liberties of black's b-12-16 group).

In case of ample liberties of surounding groups, black could start killing white by 
i) hane a17 wa18 
vital point (1-2!) b19 dead (soon black has 4 liberties on the b-line and white has 6)

or ii) 
black clamp b18 w hane a18
black b19 wd19 (white has 7 liberties vs. black's 5)

or iii) because you insist, I found Bc19 peep an interesting option:
iii-a) if Bc19 Wd19, Bb18 Wa18, Ba19(ko!) very interesting;
iii-a1) if Wa17 Be19 and white cannot do sqash (oi-tsubushi(?)) with Wc18, because of self-atari (a16 is last liberty)
iii-a2) ...Wb19 ko and black can look for the 1st ko threat,
meaning that white will lose something.

(of course, white might deviate somwhere in between :-)    )

iii-a) Bc19 Wd19, Bb18, Wa17 seems possible (instead of Wa18, this hane is just a reflex) = no ko

Conclusion: Black should forget about the white upper left corner, except for ko-threats!]
;B[ai]
C[Thank you for that thorough treatment of the upper left corner question!! Wow, what a lot of analysis goes into a game of go! I am now still trying for Ko threats, but they seem to be fast running out!]
;W[lg]
C[My analysis will most probably also comprise several smaller or bigger mistakes.

Ko really adds several dimensions (time, potential, value evaluations) to the game or fights.
That's why (relatively) stronger players (should) like it in handicap games.

Your ko threat is a valid one - seen locally.
However, we do have another semeai going on between the white f-k11 group (liberties = 2+ko) and the black f12-18 group (liberties = 4).
The white group on the b-line has now 6 liberties, but black can reduce it sente to 4 liberties (then the sente is used up, and white will go for the black f15 group with also 4 liberties. Taking back the ko from now and capturing the white h11 group also takes (at least) 4 moves (bm12, L11, h8 and j9).

Hence, it seems that I gave you wrong advice when advocating ko threats on the left - or - rather black should have never allowed for the capture of h17, thereby killing the black f15 group if taken alone.]
;B[le]
C[I am really at a loss for a move here. I want to save my hk12 group but I also fear your taking my m14.]
;W[jg]
C[Yes, it was difficult, white wins the semeais.
Bearing this in mind, saving m14 by pulling out at m15 was not anymore important => tenuki was an option, making a big move elsewhere.

This is a teaching game, hence everything is different, but eventually white simply resolves by capturing L13.
White's try to capture black's n-o-13 by atari-ing at o12 (in order to connect 2 groups) would be a mistake, because black would then take the ko....

If white however also had tenukied, s/he still would have won the semeais (explained before), but might be forced to remove one of the black  groups of the board (and therewith putting stones in white's own territory).
Hence, it was a thinkable alternative (alter-naive) for white to tenuki (Why? Because black's m15, pulling out was not a ko-threat! and the semeai was already won for white).

However, there is something to say for resolving he ko as white just did:
1st: some professional advice is:
if you can capture stones (meaning: really removing them from the board) - do it! It simply leaves less/no aji behind.
Otherwise black could play for exploiting this ko-aji, e.g. by playing sequences somewhere else, which are meaningfull AND ko-threats and/or the surroundings change and surprisingly white loses with one liberty.

2nd: The move is not so small as it seems, because it allows for endgame in the upper black sphere.]
;B[jf]
;W[nh]
C[1) Separating two white groups by making a bamboo + peep at Bp13 would have been an interesting option for black.

2) Alternatively, extending down to s15 protects the black corner AND intends to lay waste to the eye shape of that group. White then had to take those two stones n-o-13 in order to survive by connecting.

3) If black would have gotten 1) p13 AND 2) s15, white's group would seem un-rescuable dead.

Hence, 2) black s15 has a nice double-function.

The question remains, why white did not play herself with the last move.
(Proverb: "My opponents good point is my own")

4) White will lose some points (by not capturing black stones in the jkm14 area,) but gets nice strength for the right side group. 
White has no debt or burden.]
;B[og]
C[I was too focused on rescuing my group of 6 stones at hk12 to even consider the possibility of isolating your right hand upper group. I now see the beauty of S15, however I must first do a triple peep, and maybe I can play something afterwards.]
;W[oh]
;B[kg]
;W[lh]
C[Last move I failed to write a comment, because I hit the submit-button by chance.

Your double peep was an effective , good move!]
;B[ke]
C[The double peep gave me some aji at least. Now I must focus on joining my upper central group to the upper right corner. I was still tempted here to play S15, but its value has diminshed since you have joined this group to the centre.]
;W[oc]
C["diminuished .. " good analysis.
Another group of yours lives!

Now comes a normal "shock-and-awe"-invasion.
If you had not two eyes at k13 & L14, the upper edge could even perish (...chuckle ... in handicap games).

Because of some pecularities of black's "triple peep" white's peep now isn't a real one => white could also die! (But it looks good)]
;B[nc]
C[I want to block off any contact with your previously placed stone and your h13-18 group. Also it will help define a moyo in the space in between.]
;W[pc]
;B[qc]
;W[od]
C[Blocking here, had it made more difficult for white.]
;B[oe]
;W[pe]
;B[of]
C[Trying to save the group of three stones.]
;W[qd]
C[Your move was sente.
White captured here instead of greedier hanes.
                    
Stones removed from the board have no aji anymore.
A hane to the left or right (o or r18) might look slightly bogger, but invites you to test your aji by connecting (r16) and try to survive.]
;B[qq]
C[I thought about extending from the atari with Bs15, but seeing as how I had a chance to make a bigger move elsewhere in sente, I opted for the played stone.]
;W[rp]
C["extending from the atari with Bs15" would achieve nothing!

"bigger move elsewhere" if Br3 works or leads to anything - it's big indeed.

Small remark on the terminology:
If you say "...in sente..." you usually mean, that the sequence you play IS sente for you and you are the first one to leave the local situation and play elsewhere.

If you just play "somewhere WITH your sente" it actually only means that you "play" or "make a move" somewhere (i.e. not passing :-) )]
;B[nr]
C[Trying to link up with my outside stones.]
;W[mr]
C[Although black can live now on the inside, white hopes to live and destroy the black mojo.

This is dangerous for white.

If white were peeping at q2 at the inside , s/he was sure to survive, but had to let go access to the center.]
;B[pr]
;W[ns]
;B[or]
;W[mq]
;B[op]
;W[no]
C[Unfortunately you have to play this forcing move.
White is not unhappy to answer.]
;B[mn]
C[I know. I didnt want to play my previous move, but I had to, and I know that it enables white to join his two groups!]
;W[lp]
C[White thought that Black would defend the corner group at s3!

Instead of n6, black could also have played m4 himself to avoid double atari.

A white double atari at n6 would of course been superbe!

Back to the corner:
- where would white attack?
The point is to jump in at Ws2.

Have you seen that black still can live after that (with some cuts and throw-ins at r5 and t2)???

Are you therefore going to kill white with your sente??

(Joking, still be careful about your corner, moves at r7 (atari) or s7 (link-up threat) are both sente against the corner! The throw-in defense wouldn't work anymore for black.]
;B[qm]
C[My heart was torn between this move and Bm3. Also there was Bs3, but as you said that black could survive by cutting and throwning in at t2, I thought I would strengthen my q7. I had considered m4 instead of n6, but I feared Wn6, Bo8, Wl4,Bm3, Wl3 and white has a nice wall and threatens to take the black group which has been isolated from the op portion by Wn6.]
;W[ln]
C["...Bm3.." Not Bm3 (cut) which does not work,
rather BL2 (peep) would be good.
                                
Your move r7 is agressive:
it says: my corner will not die, and I try not to let white connect or get two eyes.

But white must connect or get 2 eyes!]
;B[nl]
C[The good thing about forced moves is you dont have to think to much about them!]
;W[rn]
C["forced moves ... you dont have to think to much about them!"

Wrong!
You always have to think in Go!
1. Here was a choice between nobi o8 and capture p8. Nobi gives an eye, capture lets white force again (but sometimes it is better!)
2. Here comes a great tip:
Everyone has always the tenuki option! (perhaps here not so advisable)
Forcing moves, like sente, are relative concepts.

Think of the Sente/Gote paper I gave to you. It concerned endgame questions. If someone always thinks in terms of "Well, he just played this double sente move , it's really huge and threatening ... I have to answer!" then you miss the insight of asking yourself
"What HAPPENS after I answered (was forced). Where will s/he play next? (another (double/simple/reverse etc. sente move!)"
"What will the position/score then be?"
"Can I win this game, if I docily, submissively answer all moves/threats etc.?"
"Am I behind or in a better position?"

No matter at which skill one plays in Go, these questions are very important.

Now let's see whether you understood what I meant by throwing-in etc. for living. Or better not - because, if Black tried to capture white by peep L3 (and e.g. white replies with connect m3) and black separates white around m7 from the upper forces, then white could live by t5 (e.g. if the corner would be different and black already alive), because that makes miai of anothe eye at t4 or t6 (and the 2nd eye at r5).

If black had a chance before to peep at s6 himself (destroys) white's eye shape, then live in the corner - that would have been interesting.]
;B[rq]
C[As you have seen off my potential attack of the peep Bs6, I am playing s3 to secure the corner. I was thinking could I play elsewhere such as e3, but my calculation skills still arent great, and I thought you might seize the chance of playing s2.]
;W[sq]
C["might seize the chance of playing s2." 
You bet! That would kill.

But first this hane, which is not only endgame, rather avoiding (in sente) that black hanes instead and DESTROYS white's eye at s5.

This double peep , Black r7 + t4 against the otherwise good shape of white would be very effective.]
;B[sr]
;W[sp]
C[Now you must reply, otherwise it's ko (Ws2, Bs1)]
;B[rr]
;W[ml]
;B[kr]
;W[lq]
C[Excellent move!
Even after telephonic proposal.]
;B[km]
;W[lm]
C[Usual proverb would be:
Don't peep where you could cut! (m7)

But I see your plan...]
;B[lk]
C[I am trying to cut off your escape to the centre]
;W[mk]
;B[mj]
;W[ol]
C[A few moves afterwards, you can see that it was premature to attack like this.

If black would connect now at o9, white p9, Bo10 and Ws8 would follow = Black would be dead!!!

Remark:
White has 7 outside liberties (on the left) + one eye (which coul be destroyed by black in the fight: (Ws8) Bs7, Ws9, Br6 (peep), Wr5 (connects), Bt6 (atari on one stone + destroying eye), Ws5 (i) connects or ii) plays ko Wt5) => result: (i) White has 8 liberties + black sente  or (ii) white has 8 liberties with ko to connect at t7, black captures ko first .

How many liberties does black have? The nakade-4 would be 8 libs by itself, but black does not threat something by playing e.g. r8.

Hence, black seem to have 6 liberties (r8 will be answered = 0, n11 =1, q11 is already atari =0, +3 liberties by the 3-nakade p8+p9+p7, +1 liberty at t7, + 1 liberty because white cannot approach fast at t8 if white cuts once before at s10 (tesuji))

Many people would have thought, "hey, the black group is killed", but actually black comes only 2 liberties short.

Of course, white could bring the capturing race to a halt, do s.th. on the left outside first, threatening to connect and gather more liberties.
(Black had to live then, white connects).

BTW , you see that white p8 (killing) is better than just atari Wo10, with the option connceting at n11 or a short ladder at p8.

The blunt atari Wn11 would destroy every aji.


From here on we proceed like this: we play on some moves, then I PASS once, Black lives on the right side, and white tries to connect or live on the left. OK?]
;B[nk]
C[Sounds good to me! Enjoy your holidays]
;W[ok]
;B[nj]
;W[rl]
C[This move goes for the kill and starts a semeai.

Next Black can do Br6, Wr5,Bs7 and white t7 (perhaps better than my earlier analysis) or s9.

White would win by several liberies.

After Br6, Wr5,Bs7 I will not reply (PASS twice) and you can live with 2 (two!) moves Bt6 and Bs9 or Bs5.

White must then try to live or connect via tactics on the left side.]
;B[qn]
;W[qo]
;B[rm]
;W[]
;B[sn]
;W[]
C[The 2nd - and for the moment - last PASS!]
;B[rk]
C[Zhilao Hu, you are too kind!!]
;W[kl]
C[White would need an additional move now!

Go for the big kill! Play safe.]
;B[jl]
C[I think there will be a fight here but I am after your big group on the mn column.]
;W[jo]
C[What does one mention for good rhetoric?

Avoid the "but" - replace it by "and".

"there will be a fight AND black is after the white big group on the mn column."]
;B[jn]
C[I was tempted to play Bj5, but I think the k6 point is vital to my centre group, therefore you would have probably played there had I played j5.]
;W[jk]
C[Bj5 would have been also ok.
White had tried to complicate things then with the double hane j6.
Chances are slim now for white - doomed?]
;B[ik]
;W[ll]
;B[jk]
;W[io]
;B[hp]
;W[hl]
;B[in]
;W[hn]
C[Black should have given atari at h7, and then firmly link. 

Black still has the option of attacking at e3.]
;B[hm]
C[You know I wanted to play h7 originally but I didnt see that it was atari!! I will try it now however! I know there are risks and I think you will win the l7 stone but your group will still have now eyes and I hope to keep your corner group from joining with the lower left group.]
;W[ki]
C["h7, ...didnt see that it was atari!!"

Ahemm, now I forgot that it was atari! Seems the white group is doomed.]
;B[ho]
C[Lets wait and see. I am perfectly capabable of messing this up!]
;W[im]
C[Even with two passes, I'm not proud about my oversight.

Your h6 is perfect!]
;B[jm]
C[Well you still have the threat of atari at g7.]
;W[so]
;B[sm]
;W[bp]
;B[ao]
;W[nb]
;B[mb]
C[We are moving into an endgame situation now.]
;W[oa]
C[True. Remember: the "Endgame" is not the "End of the game", rather the stage before it.]
;B[jc]
;W[jb]
C[Black's last move is sente.
White overlooked that.
Retroactively analyzing, Wk17 or l18 could have been bigger.]
;B[kb]
;W[hc]
;B[eq]
;W[er]
;B[fs]
;W[hr]
C[Black's move looks like tesuji, but the simple cut, prepared by the peep at Bb2 would have been effective (Black cuts and captures something).]
;B[ir]
C[Indeed. I considered Bb2 as one of my possible moves too.

Tomorrow I am off skiing for a week in France, so I wish you all the best and see you in a little over a week.]
;W[gr]
C[C'est Châtel, n'est pas? Alors, je te souhaite des bonnes pistes noires pointu et pas des accidents!

N'oublie pas d'appuyer le button pour vacances.]
;B[br]
C[C'est Samoens. Merci à toi et bonne semaine!]
;W[ap]
C[Now it's too late for Bb2 because the double cuts at d2 and f2 are connected on one side already by the Bf1-action.]
;B[cp]
;W[bq]
C[Back again for a 2-point sente atari.]
;B[an]
;W[gm]
;B[gn]
C[Oops. I didnt see your move there!]
;W[fl]
C[Doesn't matter, it's not so big.
But now seems the right time to play it because your last move threatened my b-line-group.]
;B[dk]
;W[fd]
;B[fm]
;W[ma]
;B[lc]
;W[gl]
C[M17 is a Very stylish move - Good!

Black defends with good shape (and aji against White)]
;B[si]
C[I had been tempted to play directly Bl19 in my previous move, but thought it too risky.
Jetzt habe ich Deutschkurs für den ganzen Nachmittag. Bis später, Tchüss]
;W[sh]
C["tempted to play directly BL19 ..."
Black means atari k19, I presume!?

Instead of the small keima BT11, black could have played an ogeima (= large keima) BT12.

This move is called a "Monkey jump" and very often worth 9 points!]
;B[rh]
;W[sj]
C[Ooeps, he did it!

Can black live inside white's territory without weaknesses?

I expected black to retreat to the very t10 and let White take GOTE at s12.]
;B[rj]
C[I dont think black can survive, so I'll just take what I can and run.]
;W[ri]
;B[sk]
;W[si]
C[Although the right side is only ko, white has to  connect. White does not have many ko-threats, whereas black has plenty (usually the case after lost semeais somewhere else).

wL19 woul not be a small move, perhaps up to 7 points.
However, the risk on the white right side is too big. After 5 internal ko threats for blackon the s-line, black could either capture the t12-16 stones and/or capture pq17-p16 etc.

It would be completely reckless for white to play wL19.]
;B[ja]
C[That was very informative and seeing as how white so wanted to play L19, black got to thinking he could play there or possibly K19 as he has done!]
;W[ia]
C[I'm always in for a trade-off. \[http://senseis.xmp.net/?Furikawari\]

KO!  => \[http://senseis.xmp.net/?KoFurikawari\]

Keep the game flowing and interesting.]
;B[ib]
C[And so the Ko is started...]
;W[mc]
C[... the n-th move, there was (en)light(ment).]
;B[md]
;W[jb]
;B[dr]
;W[cr]
;B[ib]
;W[ha]
;B[la]
;W[na]
;B[fp]
;W[am]
;B[ie]
;W[jb]
;B[bj]
;W[aj]
;B[ib]
;W[pg]
;B[ne]
;W[jb]
C[Black still has at least 6 ko threats.
White not. Black will win this ko!

This game pulls down my rating! Despite 3 or 4 passes, white would have liked to find a way out with the big right group, but black played well there.

You win - and I hope that this game gained you some experiences and insights:
* as "atari, atrai - vulgar play"
* think of "gaining and retaining the initiative" = SENTE
* Ko is a very complex matter, it opens new dimensions in the already multifunctional positions of Go:
in handicap games, stronger players like ko, because weaker players can err often by:
- making point inefficient, bad or point losing ko threats
However, do gain experience with ko, do not fear it: 
1) the 1st thing to check out is the actual value of it (is the connection of pivotal/cutting stones  or the life of groups involved?)
2) How many ko threats does each side have?
Order them in size of importance (internal ones, non-internal big ones with a continuation , smaller ones etc. until e.g. down to just making a normal move!) 
3) Which side has more ko threats (don't forget the internal ones!) of a size which exceeds the size of the position in ko? This side is most likely to win the ko.
4) If you know that you are going to lose this ko, you could also save your ko threats for a possible later ko.

Conclusion: "Don't fear ko. Who does not dare ko, does not know how to play Go" (perhaps this proverb was about the ladder)

Check out these links by Charles Matthews on ko:
\[http://gobase.org/studying/articles/matthews/\]]
;B[pi]
C[Thanks for the time you have taken to instruct me in this game! I really have learned a lot. I have decided to play the Bq11 Ko threat as it is a good joining move and not a stone that will be lost inside your territory.]
;W[qh]
C[Therewith this ko threat is worth 2 points by itself!]
;B[ib]
;W[fr]
;B[gp]
;W[is]
;B[js]
;W[hs]
;B[os]
;W[jb]
;B[pa]
C[Es wird bald fertig sein]
;W[ob]
C[Now you understand internal ko threats.]
;B[ib]
;W[iq]
;B[ip]
;W[jb]
;B[ds]
;W[cs]
;B[ib]
;W[ks]
;B[ls]
;W[jb]
;B[bs]
;W[es]
;B[ib]
;W[mi]
;B[id]
;W[jb]
;B[pb]
;W[pd]
;B[ib]
;W[ff]
;B[jb]
;W[pl]
;B[ql]
;W[]
C[Just checking whether you're there!

I pass and we go to finish then.]
;B[]
C[Incredible !  
A JIGO 
because we agreed to 140 komi.]
;W[]
TB[lr][mc][me][ld][lb][kp][kq][ks][ms][oj][rs][sq][sp][qs][qr][pq][ps][ko][kn][eo][iq][je][im][hn][fo][fn][go][jg][jr][kd][kf][lp][kc][dm][ka][do][so][ro][no][ns][np][nq][mf][nf][oo][po][om][ok][ol][mr][mq][lo][lq][ll][lm][ln][kl][jo][mm][mk][ml][io][pl][pn][rn][rp][qp][rl][qo][ss][sl]
TW[sb][sa][gf][gs][sc][gg][gk][rg][sd][rc][qg][qb][qa][sg][sf][ra][re][rd][se][rb][rf][ca][ec][ed][eb][dd][cg][fb][fs][ac][ad][ab][aa][gb][ai][bs][qc][rh][qe][pa][pb][bg][bd][br][bh][bf][be][ae][af][ef][eg][ea][ds][dr][fa][fe][gd][ga][fh][fg][df][da][al][aq][ak][ah][ag][ar][as][cb][bj][bb][ba][ge]
C[White: 53 territories + 2*21 dead stones(B) + 34 prisoners + 140 komi = 269
Black: 36 territories + 2*35 dead stones(W) + 23 prisoners = 129
Result: W+140]
)
