Author: Robert Hyatt
Date: 17:37:29 01/13/98
Go up one level in this thread
On January 13, 1998 at 20:21:19, Carsten Kossendey wrote: >On January 13, 1998 at 10:13:53, Dan Homan wrote: > >>On January 13, 1998 at 09:55:12, Carsten Kossendey wrote: >> >>>On January 13, 1998 at 09:08:49, Dan Homan wrote: >>> >>>[snip] >>> >>>>capture extensions (4/10 of a ply) >>> >>>you mean like you extend *every* capture by that amount? then it's no >>>wonder your tree explodes ... >> >>This means I need at least 3 captures in a move sequence from the >>root to generate an extension (assuming no other extensions were >>triggered). This extension alone increases the tree size by a >>factor of approx 1.5 depending on the position. Do you use >>capture extensions, if so, what kind of increase do you use? >>If I can cut this down and still be effective, I'd like to. >> >> - Dan >> >> >>> >>>>re-capture extensions (1 ply) > >[snip] > >I do not generally extend captures. I only extend captures if the last >moved piece of the opponent is captured. (Sort of a recapture extension >without the requirement of the initial move being a capture). I use >something like 1/8th ply here. This is increased if some other criterias >are matched as well (initial move was a capture, second capture restores >material bilance, etc.) > >The only case where I extend captures of pieces other than the last >moved is when the capture target is directly next to the enemy king, but >it is not check (which gets extended anyways). I think this originates >from Cray Blitz, but I'm not too sure ... I did this, because I remember a position in a game vs GM Ivanov way back. In this position, CB could have played Bxg7, which wasn't a check, and this was crushing. We won anyway, but I was curious. I set the position up later, but mistakenly put his king on h8 rather than g8, and CB instantly found a forced mate. When I looked at the position, whether the king was at g8 or h8 didn't matter, both led to the same mate lines. But it was irritating. I later decided that any capture next to the king was going to be extended, check or not, which solved that. I tried lots of different ideas, such as a capture that was recaptured by the king, etc. But this is the one that lasted. I don't do it in Crafty, however. Although I probably do too many others...
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