Author: Vincent Diepeveen
Date: 16:16:26 12/17/02
Go up one level in this thread
On December 17, 2002 at 18:21:28, Uri Blass wrote:
>On December 17, 2002 at 18:11:20, Vincent Diepeveen wrote:
>
>>On December 17, 2002 at 17:30:36, Bruce Moreland wrote:
>>
>>if you go back in time a bit you see that i had
>>major problems with Omids article and posted it here.
>>
>>there is more than just the problems you see there.
>>
>>also look at his homepage and get the positions he tested
>>and then look to his node counts. for a mate in 2 position
>>where i need like a couple of hundreds of nodes to get to 10 ply
>>he needs 10 million nodes. then R=3 reduces that more.
>>
>>also his implementation is buggy of course. it doesn't take into
>>account problems with transpositions. a classical beginners problem.
>>
>>But most important is that verification search is not something new
>>it is a buggy implementation of something already described years ago
>>with only 'novelty' that omid turns off nullmove *completely*
>>after he finds a nullmove failure.
>
>No he does not.
>There is no point in the tree that he turns off nullmove completely.
>
>>
>>All with all a very sad article. The only good thing about it is
>>the quantity of tests done.
>>
>>The test methods and the implementation and the conclusions are
>>grammar school level.
>>
>>I do not know who proofread it, but it gotta be idiots or people who
>>didn't care at all.
>>
>>Amazingly Bob defended Omid here and said nothing was wrong with
>>the article.
>
>Bob also found that verification search is good for crafty based on his post.
>Bob is not the onlyone who defended Omid.
>
>I also defend him and you are the only poster who attacks him(even posters who
>said that it did not work for them did not say that it is very bad).
>Most of what you say is not correct.
>
>Uri
You are dreaming.
Ok to list a few bugs in his paper:
a) all his test positions are mates and he doesn't do
checks in qsearch so R=2 versus R=3 matters a lot because
of the extra ply you miss of the main search finding the
mate for you. So if your qsearch is so buggy it is logical
that R=2 works at depth==9 better than R=3 at depth==9,
this is *trivial*. It is so trivial that no serious researcher
should compare the same plydepths with each other without
taking into account time.
Because we are going to conclude that minimax search is better
than alfabeta for sure.
b) now already assuming the bug in his comparision is there to
compare depth==9 with depth==9 instead of the factor time,
then the bug is that he is just testing mates so reduction
factor matters. It is trivial to try adaptive nullmove then.
c) there is major bugs in the program Genesis looking at the
branching factor differences between R=1, R=2 and R=3.
I do not know a single serious chess program that has
such a difference.
d) Genesis needs way too much nodes to get to a decent plydepth
when compared to even programs doing checks in their qsearch
and extensions in nominal search. For mate in 2 he needs like
10 million nodes to get to depth == 10.
e) illegal position in his testset.
f) his algorithm is not new. It is a rewrite of something already
existing and he rewrote it wrong. He has a bug in his verification
search. You can easily proof it by using transpositions.
g) It won't detect a zugzwang for sure simply because of transposition
bugs. Therefore the only claim can be that it is enhancing tactical
abilities of his program. Therefore it is crucial to also test
different forms of adaptive nullmove (with different depths to
go from R=3 to R=2).
h) It is unclear why he concluded verification search is better using
his own data.
a) more Fullwidth search than verification
clearly finds more positions.
b) R=3 uses less nodes than his verification search.
it is very unclear how he concludes then that verification search
is better. It's topping nowhere a list of 'this works better'.
i) Even from where i sit and without having genesis i can already smell
that adaptive nullmove works better than his own verification search.
his beloved verification search you can easily write down what it is
doing on paper. It's simply avoiding to nullmove last few plies
initially. So there is always a form of adaptive nullmove that is
going to completely outgun it simply.
j) the testset is just basically mating positions in all tests.
that's a very dangerous ground to conclude things.
Note that at depth == 10 ply i solve with diep with R=3 i solve far more
positions in way less nodes than this guy ever will. This testset is just
too simple.
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