ed wrote:Mark Uniacke wrote:I agree they are the two general purpose major advances although there are other ones that also offer extra Elo, like futility or even eliminating losing captures from the quiescence search. There are also many other search improvements which overlap with 1 & 2 and hence are much less effective, but without 1&2 existing then these other search improvements would be effective.
Also although not a general technique I have found search extensions to be extremely effective and I can see how implementation of search extensions could have another big impact on the strength (or otherwise) of a chess program.
I don't think it is possible to rely on the displayed search depths because some programs don't display their true depths. Additionally as you well know there are many factors, sometimes it is not the iteration depth but the importance of not pruning a critical new line of play that is key.
15 years ago a number of us were guilty of tuning against position test sets which were usually tactical. This was compounded because important publications like CSS used to run features on new programs performing against the BT test or the LCT2 test or ...
So it also became even commercially important to do well in these test sets. Of course there is a very loose relationship between test positions and chess strength in games and I think understanding the reasons for that are very important in understanding where chess strength in games comes from.
It is your last statement where we disagree. It is clear to me that the big + and - in Elo comes from search and the gradual accumulation of rating points comes from eval. I believe the two mentioned search breakthroughs above can be implemented in various different ways and the range of strength improvement is still quite large.
So I think there is plenty of room still to improve chess programs in both search and eval but I believe ultimately more strength comes from the search than it does from the eval.
Hi Mark and Uri,
Our discussion is as old as the birth of computer chess and we should keep it going and redo at times until we are in agreement.
My take, let's evaluate some history:
Richard Lang ruled the mid 80's till about 1992. Richard has admitted that his domination mainly came from his advantage of the better hardware he got from Mephisto. IOW: search dominance.
1991/92: Tasc came with the ChessMachine hardware 2 times faster than his hardware, Richard lost his world-title. Search dominance again.
1993/1994: Intel enters the scene, the Pentium, the end of the dedicated industry. You win the 1993 WCCC in Munich.
1996: Rebel8 tops the SSDF with a +60 elo gap. What was Rebel8 about? Search improvements mainly. Search rules.
1998: Fritz5, the introduction of a new concept, Nullmove. Frans rules the computer chess world for a couple years. Search, search, search...
Eventually other programs catch up, Fritz loses its superiority.
2000/2001: Shredder discovers LMR and tops all rating lists for years to come. Search did the trick again...
But, but, but... and this is crucial, eventually other programs catch up, ending the Shredder hegemony.
We are now living in the Rybka era, nobody yet knows its secret. Search only? The 2 of you seem to suggest it.
I disagree.
Why?
Although (I think) it's a proven fact that search has ruled the computer chess area (see above history) from its early existence till now the tendency can be quite misleading for the future, it certainly can't be automatically assumed as the 2 of you do.
My thesis: while it is certainly true that implementation matters it's wrong to assume this can explain the big difference between Rybka and the other tops. It's like saying Vas is a search genius, the rest is incompetent. I don't buy that, even if it is true eventually others will catch up.
Why claim the success of Rybka is search? There is no proof of that. Maybe your search (and others) is better than Rybka, who can tell?
Nowadays with ease the current tops are searching at 14-16 plies covering about all possible tactics, so what is left? IMHO, asking the question is answering the question.
Food for thought?
Ed
