DieterVerhofstadt/2021 ABC of mistakes

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[Diagram]
Mistake 1  

Should White connect at a, atari at b or play c?

Answer: b and c are good endgame but a is urgent. White has a shortage of liberties and will at least lose the 2 central stones if not connecting at a.

[Diagram]
Mistake 2  

Should White try to save his stones with a, sacrifice with b or play elsewhere c?

Answer: the top is relatively small and it's not clear how to use the remaining aji. The right side is the big/urgent area to play.

[Diagram]
Mistake 3  

After black+circle White can make the natural answer at a, flatten Black's moyo while attacking the lower right group with b or play c. Which one is better?

Answer: a is the best move here. Black's atari is either sente or costly, White makes territory and affects the group above. Also, b and c are too close to the bottom right thickness.

[Diagram]
Mistake 4  

White has a big lead (33 points). Black is trying to stage an upset. White lost 10 points by making the wrong choice between a, b and c.

Answer: a was the slow connection here. Connecting at b would already be better but c would be most efficient.

[Diagram]
Mistake 5  

White's left side group needs to pay attention to its eyespaces. Should it play a, b or c? White's choice lost another 9 points here.

Answer: White chose the dull move b. Connecting or making another eye at a would be better but the most active move is c'. Black can't play b because of a shortage of liberties.

[Diagram]
Mistake 6  

A ko has developed along the left side. Which ko threat should White play, a, b or c?

Answer: b is a local ko threat leading to more local ko threats.

[Diagram]
Mistake 7  

A skirmish has been going on in the lower right. How to continue? Turn at a, the border of two moyos? Draw out and fight at b? Or take the big point at c? White's decision lost 4 points and dropped him from 80% to 60%.

Answer: turning is best. Fighting at b is not good because the lower right is already alive. The cutting stones are disposable. The three stones are vital.

[Diagram]
Mistake 8  

White has the upper hand in this game. Should he cut at a or b? Or is cutting not very valuable and is this the right time to invade the corner at c? White's decision cost him 13 points and brought the game back in balance.

Answer: cutting straight through with b is best.

[Diagram]
Mistake 9  

White has ended the ko in the upper right and Black follows up the threat at B1 with cutting at B3. White's next move is not game losing but there was no need to spoil 35 points of a 60 point lead. Where should White play, a, b or c?

[Diagram]
Mistake 10  

This is more or less a joseki question. Should Black press at a, cut at b or connect at c?

Black's choice dropped him from 77% and 4 pts to 30% ans -2.

[Diagram]
Mistake 11  

Things are hot in the upper left. Should Black keep White disconnected at a, cut to capture at b or play the vital point of c?

Black's choice lost 2,5 points but shifted the balance to White again and was the start of lots of trouble.

[Diagram]
Mistake 12  

Black was a little confused here. Take a good look: where would you play?

[Diagram]
Mistake 13  

B1 is enlarging Black's moyo. What should White do?

[Diagram]
Mistake 14  

a cut, b connect, c sabaki

[Diagram]
Mistake 15  

a kill the aji in the corner; b forcing Black into bad shape; c sabaki

[Diagram]
Mistake 16  

This is a big mistake in the opening. After black+circle, White leads already by komi, provided he makes the right move. What is biggest?

  • a following Leela Zero's opening gospel and approaching the 3-4?
  • b following up locally, avoiding to be shut in?
  • c securing the corner while kicking Black's approach stone?
[Diagram]
Mistake 17  

Black did not hesitate to play the double hane. After the atari and connect, White can choose to follow through in the lower left witg a, sacrifice three stones and make a ponnuki at b, or save his corner at c

[Diagram]
Mistake 18  

How to respond to the cut? Counterattack at a? Or connect at b or c?

[Diagram]
Mistake 19  

How to respond to W1?

[Diagram]
Mistake 20  

How to maximize chances of living?

[Diagram]
Mistake 21  

White builds a moyo. Limit and grow (a), peep before reducing (b), or (c) play elsewhere?

[Diagram]
Mistake 22  

Black builds a huge moyo. Should White reduce (a, c), invade (b, d) or play away (e, f)? The move I chose wasn't really bad and I'm actually quite happy with it.

[Diagram]
Mistake 23  
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Mistake 24  
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Mistake 25  
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Mistake 26  
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Mistake 27  
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Mistake 28  
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Mistake 29  
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Mistake 30  
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Mistake 31  
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Mistake 32  
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Mistake 33  
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Mistake 34  
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Mistake 35  
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Mistake 36  
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Mistake 37  
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Mistake 38  
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Mistake 39  
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Mistake 40  
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Mistake 41  
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Mistake 42  
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Mistake 43  
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Mistake 44  
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Mistake 45  
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Mistake 46  
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Mistake 47  
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Mistake 48  
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Mistake 49  
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Mistake 50  
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Mistake 51  
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Mistake 52  
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Mistake 53  
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Mistake 54  
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Mistake 55  

bugcat: How about d?

[Diagram]
Mistake 56  
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Mistake 57  
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Mistaje 58  
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Mistake 59  
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Mistake 60  
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Mistake 61  
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Mistake 62  
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Mistake 63  
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Mistake 64  
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Mistake 65  
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Mistake 66  
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Mistake 67  
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Mistake 68  
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Mistake 69  
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Mistake 70  
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Mistke 71  
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Mistake 72  
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Mistake 73  
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Mistake 74  
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Mistake 75  
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Mistake 76  
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Mistake 77  
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Mistake 78  
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Mistake 79  
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Mistake 80  
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Mistake 81  
[Diagram]
Mistake 256  

Another slonection. White should block at a.

[Diagram]
Mistake 257  

W1 is heavy. The hanging connection at a is the shape to get out.

[Diagram]
Mistake 258  

W1 is taking the upper hand but there was no reason not to atari from the outside.

[Diagram]
Mistake 259  

Black has an almost perfect opening but B1 would have been better at a. It gives some shape to the weakest group and it also reduces the central moyo forming.

[Diagram]
Mistake 260  

The vital point in this position is b which Black can take in the most forcing manner by playing a first. White can ignore B1 and take b for herself.

[Diagram]
Mistake 261  

The game is already over after the kill at the bottom but B1 is not even necessary and Black can play elsewhere.

[Diagram]
Mistake 262  

W1 reduces the more developed half of the moyo but allows Black to build strength towards the less developed half. Any of a, b, c is better.

[Diagram]
Mistake 263  

W1 allows for B2 which turns the above shape into an empty triangle. Such inefficiency is usually a no-go for KataGo.

[Diagram]
Mistake 264  

Big tactical mistake by White, who should play a instead, making an extra liberty in the fight that matters. After W1, a black move at b would end the game.

[Diagram]
Mistake 265  

Turning at a is more important.

[Diagram]
Mistake 266  

a is a much better connecting shape, because if Black cut at W1 next, he'll suffer from shortage of liberties

[Diagram]
Mistake 267  

It's complicated but cutting at a would have been much better.

[Diagram]
Mistake 268  

In this case it is better to capture at a because of the sente value of the subsequent b

[Diagram]
Mistake 269  

White's central group is too weak to pull off the large scale surround of W1. A move at a strikes a better balance of attack and defence.

[Diagram]
Mistake 270  

White's wishful thinking continues. B2 cuts in sente and White's group is in dire straits.

[Diagram]
Mistake 271  

W1 is not well positioned. The idea is to use the top right aji but KataGo thinks the top left aji has more potential.

[Diagram]
Mistake 272  

The real shape point here is a. White will be forced into very small life. Forcing first at b is also an option.

[Diagram]
Mistake 273  

White should have taken the corner instead. It's difficult sometimes to know when to take the corner and when the outside.

[Diagram]
Mistake 274  

extend from a crosscut they say - it's not so easy. Atari at a or ruin the shape at b are better, combined with peeping at c to create a living group.

[Diagram]
Mistake 275  

W1 is wrong direction. The weak group is in the center. Cutting at a provides safety.

[Diagram]
Mistake 276  

This W1 is connecting the tail to the body leaving the whole to be cut off the head at A. I thought Black had shortage of liberties here but he can always capture at b.

[Diagram]
Mistake 277  

Black misses a tesuji at A.

[Diagram]
Mistake 278  

Black has found the tesuji but postpones its execution at A, while there is no time for that. White can now force at W2.

[Diagram]
Better - W4 at B1  
[Diagram]
Mistake 279  

Black is in trouble at the right side. Before living, I decided to play this forcing move. The problem is that it loses a possible atari in the fighting on the right. KataGo doesn't show any variation where it shows up but I assume that's the reason for losing so many points here.

B3 is also a weak attempt at living. Black should play A.

[Diagram]
Mistake 280  

I learned the clamp from Dwyrin but here it's not appropriate and White should simply hane at B2 because next A doesn't work for Black.

[Diagram]
Mistake 281  

White has gotten into a bit of unnecessary trouble here and W1 is too much. White should give up that stone and make an eye at A.

[Diagram]
Mistake 282  

Things are going better again but W1 here is too soft and White should push up at A.

[Diagram]
Mistake 283  

No reason to be fancy here, just cut at A.

[Diagram]
Mistake 284  

White can trade here: capturing the bottom is larger than saving the lower left. A wins the capturing race.

[Diagram]
Mistake 285  

This move is too patient. Clearly pressuring the corner at A is more assertive.

[Diagram]
Mistake 286  

Perhaps not so much a slonection as a not-so-urgent connection. When B2 cuts White's shape is affected while Black takes central influence, so W1 loses lots of its value. Instead White should connect at B2:

[Diagram]
Better  

This time Black's shape is problematic while White's cut off left group is not so easy to attack. White has many good places to go now (a, b, c) and Black can't be everywhere. I get the idea but I find it hard to implement and follow through.

[Diagram]
Mistake 287  

I thought the turn at W1 was a nifty way to respond to black+circle but KataGo thinks White should pressure the upper right now and treat the lower right more lightly. A and C are obvious moves but B, creating some aji at the center, is a subtle move.

[Diagram]
Mistake 288  

Another lazy bamboo. White can afford to cut at A.

[Diagram]
Mistake 289  

When having a surplus of stones, B1 is a slonection. Black can play more forcefully with the descent at A, prompting White to scramble at B then block in sente again at C.

[Diagram]
Mistake 290  

B1 is even worse a slonection. It looks like honte but Black should really take sente now with A to launch a splitting attack with all that influence built up.

[Diagram]
Mistake 291  

It all goes downhill after this cut at B1. In this case Black should connect at W6, fixing the shape to pressure White's weak diagonal in the corner while allowing White to link up to the left. THere's just too much going on here to play this forcefully. Go is a difficult game.

[Diagram]
Mistake 292  

W1 hits a shape point but would have been better at A to put the proper pressure on the Black stones.

[Diagram]
Mistake 293  

White misses an opportunity here to harass the top right group.

[Diagram]
Mistake 294  

Not only a slonection but a heavy one too. Instead, White should give up those light stones and reinforce towards the left side.

[Diagram]
Mistake 295  

A slonection if ever there was one. White should keep up the pressure at A, then ignite the aji at B and C. W1 allows Black to live in sente at A himself and next take care of the aji.


bugcat: As an EGF 5k, I can definitely see myself making this connection, especially if I was under any kind of time pressure. I find it helpful to justify a like this, with a prepared sequence that creates a net to defend against the potential cut. It might not be the best endgame but the idea is made clear.

[Diagram]
#295 -- bugcat's variation  
[Diagram]
Mistake 296  

A case of atari blindness. White should simply play A. If Black at W1 next, then White should simply atari at C. I saw B instead which puts myself into atari and had not considered C.

[Diagram]
Mistake 297  

W1 allows Black to turn the capturing race into a multi step ko?. Black has a lot of ko threats in the lower left and the centre, while White has virtually none. KataGo will find ways to still win but WHite could have simplified a lot by taking A for himself.

[Diagram]
Mistake 298  

While big, W1 should be at the urgent point of A. Black can cut off the 3 stones or kill the whole top.

[Diagram]
Mistake 299  

W1 is like a declaration of victory, while White is not ahead. A is necessary to stay level, while Black can't pull off a living invasion.

[Diagram]
Mistake 300  

W1 is a 2 point reverse sente. A is bigger than that.


DieterVerhofstadt/2021 ABC of mistakes last edited by bugcat on October 13, 2021 - 20:25
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