Author: Robert Hyatt
Date: 18:54:51 10/29/98
Go up one level in this thread
On October 29, 1998 at 19:01:24, James Long wrote: >Hello all, > >I've been playing a bit lately with extensions. >One issue I've been wrestling with is when to say "enough." > >I limit the number of extensions that can be done >in one node to two ply. I'd be interested to hear >if anyone has played with limiting the extensions >throughout an entire branch. you are on *very* thin ice here. you tread on the possibility of having a search that never terminates... unless you do something to be *sure* you can only extend two plies here if you extend one ply either before or after this search... IE if you *average* one full ply of extension for every ply of search, you won't terminate, but that is less likely than when you extend too far (2 plies of extension per ply of search is dangerous).. > >The two problems below are from WAC. The first run >is from Tristram v3.37, the second from what will soon >be v4.0. In *this* case, the extensions appear to >be a win. Actually, they appear to be a win >throughout the suite, but I've seen a few instances >on ICC that the program appeared to take too long >to get through an iteration. Even though the second >run came up with a mate (an easy one), I'm concerned >with the fact that the first iteration went nine moves deep. > >Similiar experiences? a hard one for me is wac141. I get the fail high on the key move *very* quickly, but some versions have needed over 5 minutes to find the mate in 6, when they needed 15 seconds to fail high... the only thing I'd add is that solving tactical problems and playing real chess games are not always the same thing... and improving one can hurt the other... > > >position 009 >3q1rk1/p4pp1/2pb3p/3p4/6Pr/1PNQ4/P1PB1PP1/4RRK1 b - - 0 1 > >solution is Bh2+ >Depth Time Nodes Score Princ. Continuation >----- ---- ----- ----- ------------------- >1 ... 0.00 226 -1.793 Rxg4 >2 ... 0.04 462 -1.997 Rxg4 Bf4 >3 ... 0.11 2970 199.991 Bh2+ Kh1 Bg3+ > >my move is Bh2+ >[right][3][0.108][26283][3.00] > > > >position 009 >3q1rk1/p4pp1/2pb3p/3p4/6Pr/1PNQ4/P1PB1PP1/4RRK1 b - - 0 1 > >solution is Bh2+ >Depth Time Nodes Score Princ. Continuation >----- ---- ----- ----- ------------------- >1 ... 0.01 411 199.991 Bh2+ Kh1 Bg3+ Kg1 Rh1+ Kxh1 Qh4+ Kg1 > Qh2# > >my move is Bh2+ >[right][1][0.014][15807][1.00] > > >--- >James
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