Author: Tony Thomas Karippa
Date: 01:29:15 02/28/06
Go up one level in this thread
On February 27, 2006 at 22:12:59, Robert Hyatt wrote: >On February 27, 2006 at 19:35:54, Tony Thomas Karippa wrote: > >>On February 27, 2006 at 14:53:26, Robert Hyatt wrote: >> >>>This will be relatively short and sweet. >>> >>>As most know, I've been doing some major revisions to Crafty, preparing for the >>>next WCCC event. These revisions are affecting the evaluation code which has >>>been really ripped asunder and partially restored to sanity, and the search >>>which includes some new reduction code replacing the older futility pruning done >>>near the frontier, where the reduction stuff is done almost everywhere. >>> >>>I knew there would be a few eval issues as king safety has mainly been >>>simplified with a couple of glaring holes left open for later work. I was >>>really interested in the new search code because the speed/depth looked very >>>good. >>> >>>So I'll start there, briefly. I've tested the new code in lots of nunn-type >>>matches, as well as in test suites. So far, the new search solves every >>>tactical suite I have tried in less total time than previous versions, which was >>>surprising since the late move reduction idea often delays tactical solutions by >>>hiding some strange threat moves that get reduced and therefore look >>>ineffective. But happily, it has gotten better tactically in the same time >>>frame. Yes it might take an extra ply or two to find the key move, but it is >>>getting those 1-2 extra plies done more quickly so that the key move is _still_ >>>found faster than the older versions. So that looks good (so far). >>> >>>Another thing I watched for was for a sudden "fail low" to pop up unexpectedly >>>in a game, and I didn't see a one. Yes we had fail lows, but they were >>>progressive and were the result of bad positions getting worse, not being +1 and >>>suddenly seeing -3 after our opponent made an unexpected move. So for the >>>moment, the current search appears to be solid. I have spent a ton of time on >>>it in past weeks running test matches against older versions, running test >>>suites and going over the output carefully, etc. >>> >>>Now I'm back to finishing up the eval. >>> >>>If you look at the Rascal game (round 8 I think) Crafty played a really lousy >>>move 28. Nh7+. After looking at this a bit, white has two choices. The knight >>>must move (attacked by pawn) and it can retreat to f3 (sane) or check on h7 and >>>get trapped (insane). Crafty chose the latter for lots of reasons, mostly >>>wrong. The king has to move to the e-file, as the g8 square is attacked by a >>>white bishop, and the f8 square where the king now stands is attacked by the >>>knight. So Crafty is pushing the black king into the center of the board. The >>>only problem is, queens are gone, and there is not a plethora of material >>>available to attack the king in the center, and in fact, with the knight stuck >>>at h7, nothing happens at all. This was just an evaluation error caused by >>>recent changes to king safety that were considered "temporary at best". I had >>>to reduce the king safety scores so that we could tune the other scores for >>>pieces and not keep seeing unusual moves that were a result of big kingsafety >>>swings, screwing up our ability to compare changes to see which was better. >>> >>>Another issue was that Mike/I did zero book preparation, which showed. On Sat >>>and again on Sunday we played a horrible Sicilian line (I think against Fruit, >>>then again against Glaurung) where we then played Bg7 taking the bishop out of >>>play, and then castling that way as well resulting in a cramped position. >>>Against Glaurung we actually broke the bind, but the bishop never got into the >>>game still and we were eventually squeezed to death. I should have warned Mike >>>to avoid Sicilian positions because the king safety is simply not ready yet and >>>it particularly gets into wild things when both sides castle opposite, which >>>didn't happen here. >>> >>>My next plan of attack is to take the evaluation and continue to simplify and >>>clean things up, and then fill in the missing holes as necessary after watching >>>lots of games. Crafty's endgame skills are slowly returning as other eval terms >>>are fixed and no longer swamp the important terms in endgames. I doubt any >>>parallel code will be changed unless I end up on some sort of hardware with an >>>unexpected "issue" that needs addressing, so until May, the Eval is going to be >>>the focus for the group of folks helping me work on this stuff... >>> >>>I was quite happy to not play "certain opponents" and get drowned with incessant >>>banter about nonsense, so that was a welcome change. :) Although we had some >>>of that "banter" on channel 64 frequently, but I just generally tuned channel 64 >>>out and enjoyed watching a couple of games along with the Crafty game... >>> >>>I believe this new version, when done, will end up being significantly stronger >>>than anything released in the past from the Crafty series. How it will compare >>>to the "front runners" will be seen in a few months, although it will >>>occasionally play on ICC as well. I will add that I have a "random rotation" >>>set up on ICC so that the most recent version does not play all the time to >>>avoid any tuning issues that might come up. :) I have several older versions >>>that now "claim" to be version 20.3, to make it more difficult to tune against >>>prior to the WCCC. Once the WCCC arrives, the current version will again become >>>public and I'll start to work on ideas for next year... >>That's one of the thing I like about you, you never give up, always thinks >>positve and continues to improve crafty. Many who started programming the same >>time as you have already quit, or hadnt made any progress in many years. Good >>luck in WCCC Professor. >>Tony > >"many who started.."??? > >My first program played its first move in 1968 on an IBM /360 model 40. Know >anybody that has actually been working on a chess program that long? Much one >that is still doing the grind? :) > >two more years and it will be 40 years ago... :) I was kind of referring to the winboard Era. 40 years is quite a long time, your longevity is surprisingly good.
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