Author: Robert Hyatt
Date: 09:02:29 10/25/01
Go up one level in this thread
On October 25, 2001 at 06:37:00, Mike Hood wrote: >There have been a lot of posts (over the years) about how to make engines >weaker. This is an interesting question that I'd like to revive. I mean, it's >not just about getting to the top of the SSDF list. Very few people who buy a >current chess program at its full unleashed power stand a chance of even drawing >against it. It's a matter of playing enjoyable (and instructive) chess in your >spare time. > >I'm disappointed with most of the handicap levels in chess programs. Everything >from "Drunken Assassin" to "Paranoid Scaredycat" delivers poor chess, making >stupid blunders that anyone with an ELO rating over 1000 can take advantage of. >The only successful handicapping that I've seen is limiting the ply depth of the >search. Limiting the ply search of an engine to 4 (or maybe 6) ply leads to the >engine playing solid but beatable chess. Maybe I'm just speaking from my own >limited perspective as a 1550 player, but I have the impression that the >blunders made by a plydepth-limited engine are very "human". I don't think this works. I ran some tests on one of the chess servers once with a very limited search depth and still saw ratings of over 2200 at times. Bruce ran a version of Ferret on ICC with a time limit of milliseconds per move and it too was in the 2200 range if I recall correctly. The problem is that against weaker players, even shallow searches see through their simple tactics, and you _still_ have the full positional evaluation of the program, with weak squares, pawn structure, king safety, etc. to guide the program. If you reduce the search depth, you only reduce tactics. You won't find a 1200 player that understands much about pawn majorities, weak pawns, king safety, etc. You end up with a program that is tactically weaker, but still positionally very strong. And (IMHO) it just doesn't "feel right". IE weak players will let me wreck their pawn structure where a shallow search program will not. > >I think Chessbase's "Sparring Mode" makes a choice based on a limited ply >search, then announces a warning if it sees a better move at a deeper depth. >Right? I'm not sure what Chessbase's "Friend mode" actually does. It seems to >play reasonable chess while it's in a level game, but when it's winning it >throws away the victory. Yesterday I played a curious game against Fritz 6 (in >Friend mode). After 40 moves it announced Mate in 4 against me. After 70 moves I >managed to reach a draw. > >But maybe I'm getting away from my reason for posting this message... my >question is: What IS the best way to handicap an engine? Should it be done on >engine level? Or should the handicapping be done by a meta-engine interface that >looks at an array of valuations for the n legal moves and says "Let's pick that >one"? I think this is an engine issue. The tactics _and_ the positional skills need to be toned down in parallel, so that it becomes dumber both tactically _and_ positionally... A tactically weak but positionally strong program will still give a weak human lots of trouble. A tactically strong but positionally weak program will do the same. Both need to be limited, IMHO...
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