Life In 19x19
http://www.lifein19x19.com/

live-live or semeai?
http://www.lifein19x19.com/viewtopic.php?f=15&t=553		 Page 1 of 1
Author:  entropi [ Mon May 17, 2010 2:35 am ]
Post subject:  live-live or semeai?
Click Here To Show Diagram Code
[go]$$B
$$ . . . . . . . . . . . . |
$$ . . . . . . . . . . O . |
$$ . . . . . . . . . . . . |
$$ . . , . X X X X O O O . |
$$ . X X X O O X O X X X . |
$$ . X O O O . O O X . . . |
$$ . . . . . . . . . . X . |
$$ --------------------[/go]


My question is not specifically related to that position. I only put it there as an example.

My question is whether there is a rule of thumb for white to decide whether to live (letting also black live) or kill (going for semeai)? Reading the complete sequence is of course always possible but sometimes requires too much time. I wonder whether there is an easy way to count the (effective) liberties of each group in similar situations.

Thanks in advance for the eventual answers.
Author:  SoDesuNe [ Mon May 17, 2010 3:19 am ]
Post subject:  Re: live-live or semeai?
Rule of thumb is (in my opinion) something like: Do I need the points or not?

In your example for instance, you could go for life and get Sente. I think this would be a very good result for both sides.
Author:  Solomon [ Mon May 17, 2010 3:43 am ]
Post subject:  Re: live-live or semeai?
Assuming both options are, in fact, available to you, the decision would simply have to be made based on whether you have the lead or you're behind. For situations when you're behind, you may need to go for the kill instead of dual life. That's as far as rules of thumbs will go I think, just understanding the current global situation that you're in.

Regarding shortcuts to help you make the decision any faster, well...I don't think there's much. You can count liberties, sure, but that can only get you so far. I don't think there is a golden answer here; there is no easy way to quickly make a rational decision on whether to play a "meltdown move" or go for mutual agreement. It has the same vibe as asking "Is there a shortcut or a quick way to read ladders?".

I mentioned "meltdown move" earlier. If you haven't heard the term before and/or you're curious as to what it means, I would recommend reading Rin Kaiho's "Golden Opportunity". It's a very good book, especially for your level, and they cover decision-based moves that you discuss (basically, a meltdown move in your example would be the move that goes for the semeai rather than dual life; another example of a meltdown move would be one that chooses a desperate ko to kill a nearby group rather than make two eyes in gote).
Author:  daniel_the_smith [ Mon May 17, 2010 4:46 am ]
Post subject:  Re: live-live or semeai?
Here's a flow chart (minus the chart):

Code:
Can I completely read out the semeai?
a.  Yes: choose most profitable move. [*]
b.  No: Do I absolutely need the points?
b.1      Yes: Play & Pray.
b.2      No: Dual life.


[*] If you really, really want to win the game (e.g. in a tournament) maybe you should choose certain dual life in some situations even if you think you can win the semeai to avoid giving your opponent chances.
Author:  entropi [ Mon May 17, 2010 5:22 am ]
Post subject:  Re: live-live or semeai?
Thanks for the replies. They are (so far) all in the same direction: if you cannot read out and you are ahead, choose the safe way. That's ok but what if the game is balanced?

Considering the example I gave, the difference between dual-life and killing-black is about 20 points (if I am not mistaken). How much ahead do you have to be to refuse the chance of winning 20 points? If the game is already that far, sente is hardly more valueable than 20 points except of course there is another big semeai or L&D situation (or am I wrong with that?).

When I asked the question, I was more thinking of something like, "L group or an N space notcher or a door group etc, takes between X and Y moves to capture + the outside liberties, etc"... Just as a quick reference for using in fast games where you cannot read out all variations. It would be like the number of liberties of big-eyes (4 is 5, 5 is 8, blabla kind of thing http://senseis.xmp.net/?FourIsFiveAndFiveIsEightAndSixIsTwelve).

Anyway, thanks again for the replies.
Author:  Kirby [ Mon May 17, 2010 2:38 pm ]
Post subject:  Re: live-live or semeai?
I think the heuristic is easy: Always play the move that increases the probability of winning by the greatest amount.

entropi wrote:
How much ahead do you have to be to refuse the chance of winning 20 points?


Of course, it depends on what the chance is. If the probability of getting 20 points is high, then playing a move to try to get the 20 points might increase the overall probability of winning the game. If the probability is low, you can look at what happens as an alternative. If there's a good chance that you're going to lose a lot of points, then playing the move might decrease the probability of your winning the overall game.

Bottom line: play the move that increases the probability of winning by the greatest amount.

Bottom bottom line: This is much easier if you can read it out completely ;)
Author:  Bill Spight [ Mon May 17, 2010 2:49 pm ]
Post subject:  Re: live-live or semeai?
When in doubt, go for the kill.

This sounds like the opposite of my proverb, "When in doubt, tenuki." But the point is the same. You will learn more by going for the kill. ;)
Author:  Dusk Eagle [ Tue May 18, 2010 8:50 pm ]
Post subject:  Re: live-live or semeai?
I think you may also want to consider who has more to gain from killing their opponent's group. If your group in the semeai is a lot smaller than your opponent's, but still has around the same number of liberties, you might be more in favor of going for the kill than you would be in the opposite position.
Author:  daniel_the_smith [ Wed May 19, 2010 12:55 am ]
Post subject:  Re: live-live or semeai?
You mean like a "flower-viewing semeai"? Hehe
Author:  tj86430 [ Sun May 23, 2010 9:46 am ]
Post subject:  Re: live-live or semeai?
There are some thoughts in the solution to this problem: http://senseis.xmp.net/?CapturingRaceExercise2#diag1
Page 1 of 1 All times are UTC - 8 hours [ DST ]
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
http://www.phpbb.com/