A tricky endgame problem.
A fun reading problem.
Or, if you know the theory, the first move is obvious.
Enjoy!
Edit: Solution, found by ez4u.
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| Author: | Bill Spight [ Fri Oct 25, 2013 9:23 am ] |
| Post subject: | Where to poke your nose? |
A tricky endgame problem. A fun reading problem. Or, if you know the theory, the first move is obvious. Enjoy! Edit: Solution, found by ez4u. |
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| Author: | emeraldemon [ Fri Oct 25, 2013 9:32 am ] |
| Post subject: | Re: Where to poke your nose? |
| Author: | hyperpape [ Fri Oct 25, 2013 12:57 pm ] |
| Post subject: | Re: Where to poke your nose? |
Theory? I don't know no theory. But I think I heard a rule of thumb once. |
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| Author: | Codexus [ Fri Oct 25, 2013 1:56 pm ] |
| Post subject: | Re: Where to poke your nose? |
I think I got it... |
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| Author: | jts [ Fri Oct 25, 2013 2:40 pm ] |
| Post subject: | Re: Where to poke your nose? |
| Author: | Bill Spight [ Sat Oct 26, 2013 9:12 am ] |
| Post subject: | Re: Where to poke your nose? |
Well, no cigar yet. Here's a hint. |
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| Author: | synopsis [ Sat Oct 26, 2013 10:35 am ] |
| Post subject: | Re: Where to poke your nose? |
If all plays are one point, why does the order make a difference? |
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| Author: | Cassandra [ Sat Oct 26, 2013 10:39 am ] |
| Post subject: | Re: Where to poke your nose? |
synopsis wrote: If all plays are one point, why does the order make a difference? E.g. the number of subsequent threats to (e.g.) destroy another point must be considered. |
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| Author: | Bill Spight [ Sat Oct 26, 2013 10:44 am ] |
| Post subject: | Re: Where to poke your nose? |
synopsis wrote: If all plays are one point, why does the order make a difference? Well, if all plays gain one point, order can matter. See http://senseis.xmp.net/?PlayingInfinitesimals But in this case all plays gain less than one point, and the largest play is correct.
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| Author: | Bill Spight [ Sun Oct 27, 2013 6:51 pm ] |
| Post subject: | Re: Where to poke your nose? |
Well, the long open corridor seems to be attractive. But White can do better. Here are some variations to show how Black gets jigo if White starts in that corridor. Edit: Can't we show an 11x11 board? |
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| Author: | ez4u [ Sun Oct 27, 2013 9:08 pm ] |
| Post subject: | Re: Where to poke your nose? |
Bill Spight wrote: Edit: Can't we show an 11x11 board? No, it's a limitation in eidogo. We checked it in another thread but I forgot where. Meanwhile. |
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| Author: | Bill Spight [ Mon Oct 28, 2013 8:57 am ] |
| Post subject: | Re: Where to poke your nose? |
ez4u wrote: Bill Spight wrote: Edit: Can't we show an 11x11 board? No, it's a limitation in eidogo. We checked it in another thread but I forgot where. Meanwhile. Bravo, Dave!    of the solution gains 15/16 of a point instead of 7/8, like the other plausible moves. The theory of corridors with the intruder vulnerable to a possible atari was developed by David Wolfe. See Mathematical Go, by Berlekamp and Wolfe. (We are talking about corridors without stones in them.) When you have one closed corridor of length 1, atari is not a threat and everything acts as usual. The same thing is true with two closed corridors of length 2, which are miai to produce a closed corridor of length 1. And the same thing is true with four closed corridors of length 3, etc. Otherwise, when you have both open and closed corridors, one pair of corridors acts as a unit: the longest closed corridor and the shortest open corridor. They act like a closed corridor with a length equal to the sum of their lengths minus two. In the problem the longest closed corridor has length 4 and the shortest open corridor has length 3, together they act like an open corridor of length 5. The move in it gains 15/16 of a point. But we could have had the longest closed corridor with length 3 and the shortest open corridor with length 4, and the same would be true. This example illustrates that. |
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I will have to think about this some more...
although they both push into a space of the same length. The center corridor looks like it should be worth more, but note that 
and 
, it is another 4-space corridor that is worth the same as the one on the left edge. Therefore at best for Black it is a corridor worth something less than the one with