Author: Johan Melin
Date: 06:28:46 10/24/00
Go up one level in this thread
On October 19, 2000 at 22:07:42, Michael Neish wrote: > >Hi, > >I wonder whether anyone might be able to explain why my program cannot see the >solution to BT2630 #3 below > >[D]5r1k/p1q2pp1/1pb4p/n3R1NQ/7P/3B1P2/2P3P1/7K w - - > >The solution is 1. Re6, leading to the following tactics: > >1. Re6 Kg8 >2. Rxh6 gxh6 >3. Qxh6 f5 >4. Qxf8+ Kxf8 >5. Ne6+ forking King and Queen and gaining material. Hi, I think it is a null move problem. Consider the line: 1. Re6 Kg8 2. Rxh6 gxh6 3. Qxh6 null Depending on your implementation of null move, this line might use the full 8 ply. If your program does not recognize the mate-in-1 threat, it will need an extra ply. I would suspect that HIARCS can see the mate-in-1 threat. This helps both by avoiding the null-move oversight, and perhaps with extensions on such threats. /Johan Melin >My program does not see this if it searches 8-ply deep, even though it is doing >check extensions, and should therefore see it (I think) because there are two >checks in the sequence. > >If I make it do a 9-ply search it does find the right move (but well over the >time limit), and funnily enough, the PV that it gives (the correct one) extends >to eleven ply (because of the two checks). > >So we're going from not seeing far enough at 8-ply, even though it should, to >seeing further than you need to at 9-ply. > >The only strong program I have got, HIARCS 7.0, finds the move at 4-ply. Some >heavy-duty extensions at work here I think ... > >Thanks for any feedback. > >Mike.
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.