Author: Johan de Koning
Date: 01:47:34 08/16/03
Go up one level in this thread
On August 15, 2003 at 17:50:28, Robin Smith wrote: >On August 14, 2003 at 02:51:36, Johan de Koning wrote: > >>On August 13, 2003 at 17:53:30, Dieter Buerssner wrote: >> >>>On August 13, 2003 at 03:00:10, Johan de Koning wrote: >>> >>>>On August 10, 2003 at 13:57:00, Amir Ban wrote: >>>>>The log doesn't show what J8 was thinking. Apparently it thought it was mating , >>>>>because it played all moves in 0 seconds. >>>> >>>>Yet another good reason to clear out the TT at the start of every search! >>>>:-) >>> >>>Or to use the time to find a shorter mate, even when seeing a mate already. >> >>Indeed, but that didn't suit my point. :-) >> >>>What are the other good reasons for clearing TTs? >> >>1. Predictability >> IMHO an engine should just search when a search is needed. >> After all it is a tool, not a living creature. >>2. Reproducibility >> Playing and watching games is the best way to spot funny behaviour. >> Not being able to find the cause of this behaviour is pretty frustrating and >> may leave unintended features unnoticed. >>3. Complexity >> Sticky TT requires more data and more code (= more bugs). >> Complexity is not a big deal once you've got it right and you're not ever >> going to (want to) change things. But that's theory. >>4. Preprocessor >> A change of the root position might render all TT entries invalid. >> Though preprocessing is not as important as it was in the 1980s, I bet most >> engines compile at least wood and placement tables based on the game stage >> of the root position. >>5. Pondering >> If an engine has pondered the wrong move, the TT will be overwritten with >> positions that are either useless or have the wrong bound. >>6. Time management >> Admittedly implementation dependent, but the stability of the root (drops, >> move changes) is useful infomation. The time manager may get confused if >> this information is lost. >>7. Unforeseen problems >> Eg the perpetual mate that started this thread. Rather funny actually, if it >> happens to someone elses engine. But more importantly, rather instructive. >> Besides the infamous incomplete-EGDB-problem we now have the infamous >> incomplete-TT-problem. :-) >> >>... Johan > >Johan, > >For someone who uses chess engines to do analysis, rather than just playing >games, clearing Ttables is a serious flaw. Remembering partial analysises randomly is also a serious flaw. User control is the keyword I think. ... Johan
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