Author: Bernd Nürnberger
Date: 05:14:03 04/03/04
Go up one level in this thread
On April 02, 2004 at 10:45:52, Heiner Marxen wrote: >On April 02, 2004 at 10:06:10, Bernd Nürnberger wrote: > >>On April 02, 2004 at 09:10:06, Heiner Marxen wrote: >> >>>On April 01, 2004 at 07:57:27, Bernd Nürnberger wrote: >>> >>>>On March 31, 2004 at 12:35:21, Renze Steenhuisen wrote: >>>> >>>>>>(1) >>>>>>I recognized that a different move ordering delivers very alternating >>>>>>results in my alpha beta search. (I implemented null move, pv search, >>>>>>mvv/lva, some history moves, transposition table, quiescence search ...) >>>>>>Is this a bug or is this a normal behaviour? >>>>>>For example, with 3 history moves (on initial position) i get: >>>>>>[...] >>>>>> 8. 0:01.12 993512 0.00 Nc3 Nf6 d4 d5 Nf3 Bf5 Ne5 Ne4 >>>-------------------------------^^^^ >>>>>>... and with just one more history move (4): >>>>>>[...] >>>>>> 8. 0:01.28 1088694 0.00 e4 Nc6 Nf3 e5 d4 Nxd4 Nxd4 h6 >>>-------------------------------^^^^ >>>>> >>>>>Seems reasonable. >>>> >>>>Mmmh, that still is not very reasonably to me to get much different results >>>>for different move orderings. >>>>The score of the moves itself should not be affected ?! >>>>Do you have an explanation? >>> >>>But the score _is_not_ changed... see above. >>> >>>Cheers, >>>Heiner >> >> >>That's just a coincidence, another example from another position: >> >>10. 0:00.57 459625 0.22 Rxf4 Kg3 Rf7 Kxg2 Kb4 c5 Kb3 c4 >> >>... and with a slightly different move ordering: >> >>10. 0:01.78 1694656 0.01 e3 Kg3 exf4 Rf5 Rb2 Kxf4 Ka4 Rg5 >> >>That still seems somewhat strange to me ?! >> >>These are not made up strange examples. A different move ordering >>changes everything very much in my engine and I am not glad about >>this fact, whether it's natural or not, because I still cannot >>understand it .. >> >>Greetings, Bernd > >Without transposition table that is a bug, IMHO. >With TT anything can happen. > >Cheers, >Heiner I recognized the same, because I tried to figure out, what could cause this behaviour and turned certain things on/off (TT, IID, nullmove,...). Disabling TT brought me constant PVs even when changing other things... When enabling TT, the PV/score varies very quick and much and brought totally mixed up results... I will inspect my TT code. Maybe I can do something for more stability. Either it's really normal behaviour of a TT or it's a bug in the TT stuff. Let's check it... Greetings, Bernd
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