Author: Robin Smith
Date: 12:19:01 08/16/03
Go up one level in this thread
On August 16, 2003 at 04:47:34, Johan de Koning wrote: >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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