Author: Robert Hyatt
Date: 08:13:09 10/31/01
Go up one level in this thread
On October 31, 2001 at 09:56:02, Miguel A. Ballicora wrote: >On October 30, 2001 at 23:39:33, Robert Hyatt wrote: > >>On October 30, 2001 at 16:12:20, Miguel A. Ballicora wrote: >> >>>On October 30, 2001 at 15:54:06, Robert Hyatt wrote: >>> >>>>The point here is that KRBP vs KRPP might seem to be the same as a KRB vs KRP >>>>ending. The KRB has no chance of winning in a real game. There may be a >>>>contrived position where the KRB side wins, but I haven't seen any in real >>>>games yet myself. I don't want _my_ program to trade from a possiblly >>>>winnable KRBP vs KRPP, to a absolutely unwinnable KRB vs KRP ending, if I can >>>>help it. >>> >>>This is true against a computer with EGTB's, against humans it is not exactly >>>unwinnable. Particularly with "game in x" time control where it is closer to a >>>win than a draw. Practical chances are very high, it is a tough endgame to >>>defend unless you have plenty of time and know the theory. >>> >>>Regards, >>>miguel >> >> >>It isn't that hard for a computer. I ran a few such tests a few years ago. >> >>The first was KQ vs KR, with crafty playing KQ with no tablebases, against >>Crafty with KR using tablebases. Crafty with KQ won _every_ time within 50 >>moves, with no special heuristics at all other than "drive the king to the >>edge and then the corner." In fact, on a P6/200, it could win every time >>given only a couple of seconds. >> >>When Steven Edwards made me the KRP vs KR tablebase, along with the promotion >>cases, I tried this again after watching Crafty play a KRB vs KR ending and >>being unable to win it (I had never noticed that this is generally drawn). I >>tried tablebase KRB vs no-tablebase KR and the no-tablebase side had no >>problems in drawing every game. With very shallow searches. >> >>I _have_ seen programs lose drawn endings. Crafty and WchessX once played a >>KR vs KN where Crafty had the KR (no tablebases back then) and it still won the >>game. However, I would not expect to repeat that against _any_ human or >>computer I would really expect to have to play. Maybe against a 1500 it might >>win. But not against a strong player. And I am generally thinking of IM/GM >>players as the competition I play against, which simplifies things a bit. > >The last point is what you might want to reconsider. Maybe I was not clear >before, this endgame is tough for IM and GMs that do not know the theory (and >there are many). Tough even at slow time control. If they do not know the >theory, and they play blitz, Crafty will score >95%. If they know the theory and >it is blitz crafty will still score a lot of points since is very easy to make a >mistake on the crucial positions. That's all you need. > >I personally was able to hold this position against an IM many years ago with 3 >minutes on my clock only because I knew the theory perfectly and I had it >_fresh_ on my mind. He was very dissapointed not to bring the point home. >If you are a IM/GM and you knew the theory but haven't touched it in a long time >you might lose precious time before you remember. Particularly at speed chess! > >If you do not believe me, I will try to find a Nunn's quote about this. > >Miguel I will try to find a few games with this position in Crafty's huge PGN archive. I know it has played two GMs and reached this position and they drew it with no difficulty. I'm sure some can't, but the issue is that I do _not_ want to reach KRB vs KR or KRN vs KR against _anybody_ because it _should_ be drawn. If I can beat 'em with a KRB vs KR ending, then I can almost certainly beat them with a KRBP vs KRP ending.
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.