Author: Uri Blass
Date: 07:20:08 09/01/02
Go up one level in this thread
On September 01, 2002 at 09:42:46, Vincent Diepeveen wrote: >On September 01, 2002 at 02:52:13, Uri Blass wrote: > >>On August 31, 2002 at 21:11:43, Vincent Diepeveen wrote: >> >>>On August 31, 2002 at 04:00:57, Uri Blass wrote: >>> >>>>On August 31, 2002 at 03:26:01, Dave Gomboc wrote: >>>> >>>>>>This is exactly the case for Junior and Fritz and they simply do not care about >>>>>>small improvement that they can get. >>>>> >>>>>That, I don't believe. >>>>> >>>>>>They know that there are positions when the program cannot see simple tactics >>>>>>but they do not care to fix it. >>>>>> >>>>>>There are positions when Junior cannot see simple tactics and Amir ban knows >>>>>>about it but he did not fix it at least not in Junior7(some years after he got >>>>>>the information). >>>>> >>>>>That's probably because it would hurt the program overall. I'm sure he does >>>>>what he thinks is best for overall program strength. >>>> >>>>I believe that the reason for Junior is that it is not >>>>easy to fix it and be sure that you do not generate >>>>other bugs but I do not think that it is impossible >>>>to do it. >>>> >>>>I believe that in most cases >>>>professional do not work harder than the amaturs. >>> >>>they will be happy with such statements... >>> >>>Most obviously won't be able to answer that because they don't like >>>to work and prefer to stay on the beach instead :) >>> >>>>> >>>>>>There are positions when Fritz cannot see simple mate because of null move >>>>>>pruning. >>>>> >>>>>I'm sure Frans Morsch is well aware of that too. >>>> >>>>Yes but he does nothing to fix it and it does more mistakes than other programs >>>>because of null move pruning. >>>>I see no reason to use null move pruning after the first >>>>move of the pv but this is exactly what Fritz does. >>>> >>>>I already posted the analysis when Fritz finds the right move Nc6 >>>>that is winning(white is in zunzwang) but the score >>>>drop every iteration because it does not want to analyze a move that threats >>>>nothing. >>>> >>>>Here is the relevant position again >>>> >>>>[D]1n6/1P6/8/2P5/p3kp1p/6p1/1P4K1/4N3 b - - 0 1 >>> >>>>This position can happen in games >>>> >>>>Deep Fritz(black) played against Junior7(White). >>>> >>>>Junior7 already saw a score of 11.40 against itself when it played 54.c5 but >>>>Deep fritz blundered because of pruning the line that it wanted to play. >>> >>>any fritz7 comments instead of only the completely outdated deepfritz? >>>of course i tried fritz7 and it also fails miserably. >>> >>>Obviously you need to use nullmove first move after pv always >>>when you don't use alphabeta, but MTD instead. >> >>I believe that even with MTD the first ply of the pv is correct and in this >>example the zugzwang happens after the first ply of the pv(Nc6) >> >>Uri > >Please imagine what MTD is doing. Now suppose you want to quickly skip >to next ply (which in itself is great to solve testsets). > >So all you do is get a bound. Then you nullmove after the first move >*directly*. > >Do you understand why? > >Best Regards, >Vincent No I do not know much about MTD but I know that you cannot get a correct pv with MTD(constructing it from hash tables may give wrong results) so I do not like it. I have ideas to use the pv for better extensions rules(I do not do it today in movei) and if I do not know the right pv then I cannot do it. I know that the first move in the pv is always correct even with MTD. Not getting an exact score at least in the first iterations seems to me a wrong decision. I can understand not getting an exact score in the last iteration if you have a fail low and you are not interested in the exact score and you are afraid that you will not have enough time to get a better move if you try to get an exact score. Uri
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