I am white in this game. I feel like my opening is bad, catch up in mid game, and in yose stage black made a major mistake that allows me to get a lot of points for the win.

Some questions

1. For W10: I looked up the joseki and realized that it should be at S3 instead of Q5... but, given the mistake, would W14 at Q3 is the best option to guard against the Q3 cut?
2. For W20: again, I looked up the joseki and it should be either J17 or D14. Given this mistake, For W22, should I play at E16 instead of E18?
3. Is W26 extended too far? I guessed yes, since I don't have a good way to handle B27 at J16 later. For W28, I thought about attaching from below and connect at J17, but I want to be able to attack black J16 stone later. So I choose instead to play W28 at O17 and turn the top left white group from a settle group to a running group. Is this a good choice or a bad choice?
4. W40: I have never played an attachment to strengthen my weak group before... so W40 is my first try to try to settle the running group. Is this a right idea, or should I do something else?
5. W54: At this point, I am not sure what I should do. Should I play at C10, since that has more potential, and my top left group should be mostly okay, and thus I do not need to reinforce it at N13? Alternatively, I feel like the top left black corner is not settled, and a placement at R18 may work -- but I am worried that my two surrounding groups are not strong enough, and thus attacking may backfire. Am I too coward?
6. W58: I block at the outside C5 instead of C3 because I am worried that, if I let black live at the right side, my top left weak group would be endangered. Also, I am hoping to get some inference to attack the bottom middle group. Is this a reasonable strategy?
7. W68: this is another move I am not sure. I want to seal black on the left side, both for the safety of my top left group and the potential to attack black. Is E9 the right position?
8. W70: I want to attack black, but again I am not sure how to do that. So I tried a move at K7 that can separate black (though it didn't really work). Do I have better option?
9. W80: This is another move that I am not sure. I would like to seal the left side, but the sequence I used in the game should not work -- black just failed to penalize me. What should I do here?
10. B111 is a key point that I should have several moves earlier. Given the mistake, it seems to me that W112 should be at P12 instead of P11 -- or I should at least do the exchange at T15 first.


Thanks!

- you missed the vital point Q6. Q6 is the local, shared vital point. Both B and W want it.
If at Q6 (instead of G3), is it sente or gote, and why ?

- you missed the vital point E16. E16 is the local, shared vital point. Both B and W want it.

W54: The top left Black corner is very much settled. You can still reduce it, but the black group is alive and well and you can do nothing about it. Rather than C10, I would consider C5 instead.

W58: Yes, this is reasonable.

W70: It is a good idea. Even if it does not work out each time, keep playing this kind of move. Here, I would not even say it did not work, look at the amount of moves your opponent spent to connect his groups and what you got on the right side in the meantime.

W80: This is good, but W82 is a mistake, it doesn't acutely threaten anything and Black should just capture W80 w/ B83. Black is polite (mistakenly answers) and you profit.

W196: K1! (small reading exercise)

Obviously there are other points to talk about, but here you go.

It seems that you are suggesting that Q6 (circled white stone below) is sente:

Click Here To Show Diagram Code

[go]$$W
$$ . . . . . . . . . . -
$$ . . . . . . . 5 . . -
$$ . . . . . . . X 3 . -
$$ . . . . . . W 1 2 . -
$$ . . . . . . O X 4 . -
$$ . . . . . . O X . 6 -
$$ X . . O . . O O X . -
$$ . . . . . . . O X . -
$$ . . . . . . . . . . -
$$ ---------------------[/go]

or

Click Here To Show Diagram Code

[go]$$W
$$ . . . . . . . . . . -
$$ . . . . . . . 7 . . -
$$ . . . . . . . X 5 . -
$$ . . . . . . W 1 2 . -
$$ . . . . . . O X 3 6 -
$$ . . . . . . O X 4 . -
$$ X . . O . . O O X . -
$$ . . . . . . . O X . -
$$ . . . . . . . . . . -
$$ ---------------------[/go]

In these two cases, black lives, even though it has been sealed. Would the risk of being sealed enough to make the circled white stone sente?

Click Here To Show Diagram Code

[go]$$W
$$ . . . . . . . . . . -
$$ . . . . . . . . . . -
$$ . . . . . . . X 6 . -
$$ . . . . . . W 1 2 . -
$$ . . . . . . O X 4 0 -
$$ . . . . . . O X 3 5 -
$$ X . . O . . O O X . -
$$ . . . . . . . O X 7 -
$$ . . . . . . . 9 8 . -
$$ ---------------------[/go]

This is another scenario, but black is also alive, without even being sealed in.

Thank you! Some follow up questions:



A thought on C5. If black tries a 3-3 invasion anyway, would the following be a sequence to kill it? (a -> move 11; b -> move 12).

Click Here To Show Diagram Code

[go]$$B
$$ - . . . . . . . . . -
$$ - . . . . . . . . . -
$$ - . . . . . . . . . -
$$ - . . . . . . . . . -
$$ - . . O . . . . . . -
$$ - . 6 . O . . . . . -
$$ - a 7 1 2 . . O . . -
$$ - . 5 . 3 4 . . . . -
$$ - b . 9 8 0 . . . . -
$$ ---------------------[/go]

Ah yes. I haven't thought about that at all.

It happens that I had a very similar question a while back. See here.

It really is all about context and reading (and exchanges), there are plenty of reading exercises in this.

Click Here To Show Diagram Code

[go]$$B Black is dead, but why B5
$$ - . . . . . . . . . -
$$ - . . . . . . . . . -
$$ - . . . . . . . . . -
$$ - . . . . . . . . . -
$$ - . . O . . . . . . -
$$ - . 6 . O . . . . . -
$$ - 0 7 1 2 . . O . . -
$$ - b 5 . 3 4 . . . . -
$$ - . a 8 9 . . . . . -
$$ ---------------------[/go]

Click Here To Show Diagram Code

[go]$$B If a next, Black gets a ko
$$ - . . . . . . . . . -
$$ - . . . . . . . . . -
$$ - . . . . . . . . . -
$$ - . . . . . . . . . -
$$ - . a O . . . . . . -
$$ - . 5 . O . . . . . -
$$ - . . 1 2 . . O . . -
$$ - . . . 3 4 . . . . -
$$ - . . . . . . . . . -
$$ ---------------------[/go]

Click Here To Show Diagram Code

[go]$$B What about?
$$ - . . . . . . . . . -
$$ - . . . . . . . . . -
$$ - . . . . . . . . . -
$$ - . . . . . . . . . -
$$ - . . O . . . . . . -
$$ - . . . O . . . . . -
$$ - . . 1 2 . . O . . -
$$ - . 4 . 3 . . . . . -
$$ - . . . . . . . . . -
$$ ---------------------[/go]

Click Here To Show Diagram Code

[go]$$B What about?
$$ - . . . . . . . . . -
$$ - . . . . . . . . . -
$$ - . . . . . . . . . -
$$ - . . . . . . . . . -
$$ - . . O . . . . . . -
$$ - . 3 . O . . . . . -
$$ - . . 1 2 . . O . . -
$$ - . . . . . . . . . -
$$ - . . . . . . . . . -
$$ ---------------------[/go]

Click Here To Show Diagram Code

[go]$$B What about?
$$ - . . . . . . . . . -
$$ - . . . . . . . . . -
$$ - . . . . . . . . . -
$$ - . . . . . . . . . -
$$ - . 3 O . . . . . . -
$$ - . . . O . . . . . -
$$ - . . 1 2 . . O . . -
$$ - . . . . . . . . . -
$$ - . . . . . . . . . -
$$ ---------------------[/go]

It is really all messy, reading never ends, it is just useful to remember that definite territory is something that often only occurs in endgame.



Yes, pretty much so.

All this stuff of q6 neglects the fact white's already played 2 moves in the corner when he should only have played one or zero. When white played q5 push on top instead of s3 he says the outside influence is bigger than the corner. This may be wrong but it's another choice. When black played s3, r3 was a slack answer inconsistent with q5, white should hane at the head of 2 with r6 and build power. Or double hane in the corner might be ok. q3 was even worse. defending a cut that didn't work: white can play r6 still and atari underneath if black cuts. Some tewari:

Click Here To Show Diagram Code

[go]$$Bc
$$ . . . . . . . . . . -
$$ . . . . . . . . . . -
$$ . . . . . . . . . . -
$$ . . . . . . . a . . -
$$ . . . . . . O X . . -
$$ . . . . . . O X . . -
$$ X . . O . . 2 O 1 . -
$$ . . . . . . . 4 3 . -
$$ . . . . . . . . . . -
$$ ---------------------[/go]

2 is solid and simple, maybe not best but not bad. Then 3 and a are miai, but probably a is bigger. Black chooses 3 for the corner and white plays the tiny crappy endgame move at 4 instead of a so black gets both.

Being sealed in is very bad, generally. It should make you want to cry, it's so painful. Once you are sealed in, the only thing your group is doing is making points. It has no effect on the rest of the game. Normally, groups that are alive are very thick, but when you are sealed, you can't use that thickness at all. There are no invasions it helps, and it can't be used to beat up on weak groups, or threaten things, and it can't split anything. Even if a group isn't 100% alive, it's generally more useful over the course of the game if it has access to the center.

There are rare cases where the profit is enough to make up for being sealed in, but if you play as if that is never the case, you will improve much faster for the time being. You need to learn what the rule is before you can learn about exceptions, and learn to walk before you run.

In this case (on this board), yes. Notice that not only is B sealed in the corner, but W also cuts off .

Follow-up question: of the two variations A and B, which one is better for W ?

It is a tough question for me -- both seem to be equally good. I would vote for B as a bit better, because a is a good ko threat:

Click Here To Show Diagram Code

[go]$$W Variaton B
$$ . . . . . . . . . . -
$$ . . . . . . . O . . -
$$ . . . . . . . B O a -
$$ . . . . . . O O X . -
$$ . . . . . . O X . X -
$$ . . . . . . O X X . -
$$ X . . O . . O O X . -
$$ . . . . . . . O X . -
$$ . . . . . . . . . . -
$$ ---------------------[/go]

whereas in variation A, both the descent and hane don't threaten live.

Clue : which is better, it being your turn to play, or your opponent's?

Uberdude's hint is about sente versus gote. You can think about it.

Another factor is shape. Which gives B better shape ?
One forces B to make a ponnuki; the other one doesn't.
You can also think about this one.

The ko threat is not so important in this situation.

Thank you EdLee and Uberdude's explanation! I now understand why variation A is better.

Hi GoStudent,

You now understand better why Variation A is better for W.

One thing that makes Go so interesting
(and very difficult, and frustrating) is the exceptions.

Follow-up question: suppose it is important
for W to separate from the group.
Then, after at (a), which is correct for — (b) or (c) ?

Click Here To Show Diagram Code

[go]$$W
$$ . . . . . . . . . . -
$$ . . . . . . . B . . -
$$ . . . . . . . . c . -
$$ . . . . . . . 1 a . -
$$ . . . . . . O # b . -
$$ . . . . . . O X . . -
$$ . . . . . O . O X . -
$$ . . . . . . . O X . -
$$ . . . . . . . . . . -
$$ ---------------------[/go]