Author: Robin Smith
Date: 12:21:26 08/16/03
Go up one level in this thread
On August 16, 2003 at 15:19:01, Robin Smith wrote: >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 Johan, I have analysed with all the top engines. The ones that clear hash tables are FAR worse for interactive analysis. Believe me. Robin
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