Author: Stuart Cracraft
Date: 13:46:49 09/02/04
Go up one level in this thread
On September 02, 2004 at 14:09:22, Andrew Platt wrote: >On September 02, 2004 at 09:45:25, Michael Henderson wrote: > >>>>With pruning by evaluation latest movei get it only in 10 plies but I think to >>>>change my pruning to make it see it faster. >>>> >>>>Uri >> >>is recapture extension also playing a role here?...if that applies. > >Having shaken some bugs out I'm now trying to understand where else my search >needs to be improved to get this in a reasonable time and re-capture seems to be >a key item. I played around with Crafty a bit and disabled re-capture extensions >(I left mate threat extensions in). Without re-capture things look like this: > > 9 7.09 -0.88 1. Kf1 a5 2. Rxh5 gxh5 3. Rxh5 Re1+ > 4. Kxe1 Nxh5 5. Qg5+ Kf8 6. Qh6+ Ke8 > 7. Qh8+ Bf8 8. Qxh5 > 9 8.23 +1 1. Qxf4!! > 9 8.56 +3 1. Qxf4!! > 9 9.24 +M 1. Qxf4!! > 9 41.38 10.88 1. Qxf4 Be5 2. dxe5 Rxe5 3. Bxe5 Qb6 > 4. Rd1 Re7 5. Rd6 > 9-> 41.38 10.88 1. Qxf4 Be5 2. dxe5 Rxe5 3. Bxe5 Qb6 > 4. Rd1 Re7 5. Rd6 > 10 51.88 +1 1. Qxf4!! > 10 1:05 +3 1. Qxf4!! > 10 1:22 +M 1. Qxf4!! > 10 6:22 Mat06 1. Qxf4 Bxf4 2. Rxh5 gxh5 3. Rxh5 Bh6 > 4. Rxh6 Qh2+ 5. Kxh2 Kf8 6. Rh8# > 10-> 6:22 Mat06 1. Qxf4 Bxf4 2. Rxh5 gxh5 3. Rxh5 Bh6 > 4. Rxh6 Qh2+ 5. Kxh2 Kf8 6. Rh8# > > >compared to this with both extensions (sorry about the switch from native output >to xboard output): > > 9 -88 659 4040010 1. Kf1 a5 2. Rxh5 gxh5 3. Rxh5 Re1+ 4. Kxe1 N >xh5 5. Qg5+ Kf8 6. Qh6+ Ke8 7. Qh8+ Bf8 8. Qxh5 > 9 -77 742 4591270 1. Qxf4!! > 9 23 779 4824187 1. Qxf4!! > 9 223 862 5373878 1. Qxf4!! > 9 32756 6672 48787620 1. Qxf4 Bxf4 2. Rxh5 gxh5 3. Rxh5 Bh6 4. Rxh >6 Qh2+ 5. Kxh2 Kf8 6. Rh8# > 9 32756 6672 48788236 1. Qxf4 Bxf4 2. Rxh5 gxh5 3. Rxh5 Bh6 4. Rxh >6 Qh2+ 5. Kxh2 Kf8 6. Rh8# > > >Andy. What is the nature of Crafty's recapture extension? Mine is: extend by 1 ply, unless already extended at this node, if the last move restored the material difference between the two sides to what it was prior to the start of the search.
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