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Subject: Re: MODERATION(the title is misleading and it is about programming)

Author: Josť Carlos

Date: 13:56:19 07/22/02

Go up one level in this thread


On July 22, 2002 at 03:47:32, Uri Blass wrote:

>On July 21, 2002 at 21:36:53, Miguel A. Ballicora wrote:
>
>>On July 21, 2002 at 16:02:36, Uri Blass wrote:
>>
>>>On July 21, 2002 at 14:54:40, Miguel A. Ballicora wrote:
>>>
>>>>On July 20, 2002 at 15:53:15, Uri Blass wrote:
>>>>
>>>>>On July 20, 2002 at 15:37:00, Christophe Theron wrote:
>>>>>
>>>>>>On July 19, 2002 at 23:12:28, Ricardo Gibert wrote:
>>>>>>
>>>>>>>On July 19, 2002 at 23:08:16, Robert Hyatt wrote:
>>>>>>>
>>>>>>>>On July 19, 2002 at 22:15:31, Ricardo Gibert wrote:
>>>>>>>>
>>>>>>>>>On July 19, 2002 at 21:43:40, Robert Hyatt wrote:
>>>>>>>>>
>>>>>>>>>>On July 19, 2002 at 15:50:44, Uri Blass wrote:
>>>>>>>>>>
>>>>>>>>>>>On July 19, 2002 at 15:25:48, Christophe Theron wrote:
>>>>>>>>>>>
>>>>>>>>>>>>On July 18, 2002 at 12:14:10, Robert Hyatt wrote:
>>>>>>>>>>>>
>>>>>>>>>>>>>On July 18, 2002 at 05:58:56, Vincent Diepeveen wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>>>On July 17, 2002 at 13:18:40, Christophe Theron wrote:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>On July 16, 2002 at 11:01:23, Vincent Diepeveen wrote:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>On July 15, 2002 at 13:11:09, Christophe Theron wrote:
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>On July 15, 2002 at 08:37:34, Omid David wrote:
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>I don't think using double null-move is a good idea in practice, since in
>>>>>>>>>>>>>>>>>>midgame the chance of zugzwang is negligible and thus it's superfluous (I doubt
>>>>>>>>>>>>>>>>>>if even DIEP uses it). However the contribution of double null-move is that it
>>>>>>>>>>>>>>>>>>gives legitimacy to the null-move pruning idea, proving that it _is_ a correct
>>>>>>>>>>>>>>>>>>search method (anyway, no one doubts null-move nowadays).
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>Why does double null move prove that null move is a correct search method????
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>Doing two null moves in a row means going back to standard search (a search not
>>>>>>>>>>>>>>>>>involving an illegal move like null move is).
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>I fail to see how it legitimates null move.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>Double nullmove legitimates (duh can't you use easier to spell words)
>>>>>>>>>>>>>>>>itself, for the obvious reason that it is provable now that a search
>>>>>>>>>>>>>>>>depth of n ply, where i may pick n, is going to solve any problem you
>>>>>>>>>>>>>>>>give it.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>OK, I see now.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>However, it is not true.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>Due to a nasty interaction with the hash table algorithms, just allowing 2 null
>>>>>>>>>>>>>>>moves in a row will NOT solve any problem.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>What you refer to is a practical impossibility (assuming you have
>>>>>>>>>>>>>>a efficient search) :
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>  your assumption is that from a root position r
>>>>>>>>>>>>>>  with transition of some moves to position p, side stm to move and
>>>>>>>>>>>>>>  depthleft=d:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>  r ==> p(stm,d)
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>  that you visit this position with properties that
>>>>>>>>>>>>>>  before this move you have made 1 nullmove or less.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>  so ==> r , nullmove , p
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>  Now a major problem for such an event to occur is that
>>>>>>>>>>>>>>  after 1 nullmove, sides change the side to move.
>>>>>>>>>>>>>
>>>>>>>>>>>>>Why is this a problem?  IE in my case, position P reached thru a path
>>>>>>>>>>>>>with a null-move and position P reached thru a path without null-move
>>>>>>>>>>>>>are _unique_ positions...
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>If so, your programs loses a lot of opportunities to prune because it detects
>>>>>>>>>>>>less transpositions. But maybe it avoids some problems and is benefical in the
>>>>>>>>>>>>end, I do not know.
>>>>>>>>>>>
>>>>>>>>>>>How much do programs earn by pruning based on hash tables?
>>>>>>>>>>>
>>>>>>>>>>>Today I do not use hash tables to prune the tree.
>>>>>>>>>>>I am interested to know how much rating programs earn from
>>>>>>>>>>>using hash tables to prune the tree.
>>>>>>>>>>>
>>>>>>>>>>>1)Did someone do the experiment of comparing the rating of
>>>>>>>>>>>a chess program when hash tables are used only for things like order
>>>>>>>>>>>of moves and the rating of the same program when hash tables are used also for
>>>>>>>>>>>also to prune the tree.
>>>>>>>>>>>
>>>>>>>>>>>2)How much speed improvement do programs get in middle game
>>>>>>>>>>>from pruning based on hash tables?
>>>>>>>>>>>
>>>>>>>>>>>Uri
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>Try position fine 70 with and without.  Without you might get to depth 15
>>>>>>>>>>or so.  With it you can reach depth 40.  A _significant_ gain...
>>>>>>>>>
>>>>>>>>>You're trying to drive Uri crazy aren't you?
>>>>>>>>>
>>>>>>>>>Did you really think Uri could not think of an example of a position where
>>>>>>>>>having hash tables makes a significant difference?
>>>>>>>>>
>>>>>>>>>Do you really think being able to search a position like Fine 70 to a depth of
>>>>>>>>>40 instead of 15 will make a difference in a programs playing strength?
>>>>>>>>>
>>>>>>>>>Don't you realize people are liable to react to such a reply as yours above as a
>>>>>>>>>troll?
>>>>>>>>>
>>>>>>>>>Please try to be a bit more thoughtful.
>>>>>>>>
>>>>>>>>
>>>>>>>>There was _no_ troll involved.  Point by point.
>>>>>>>>
>>>>>>>>fine 70 _is_ an important hash test. It represents a near-best-case for
>>>>>>>>hashing.  Which is the best you can do.  It increases the search depth by
>>>>>>>>at least a factor of 3x in terms of plies searched.
>>>>>>>>
>>>>>>>>Will that help the program?  Clearly in king and pawn endings I see 20+ ply
>>>>>>>>searches _all_ the time.  And _that_ definitely helps for those positions where
>>>>>>>>K+P endings are reached.
>>>>>>>>
>>>>>>>>But if you want to take a middlegame position, hashing is worth at least a
>>>>>>>>factor of 2x based on tests I have run in the past.  I can always run them
>>>>>>>>again.
>>>>>>>>
>>>>>>>>So to summarize, fine 70 was and is legitimate.  It _clearly_ shows that
>>>>>>>>hashing makes a significant difference.  I hardly see why _your_ post wouldn't
>>>>>>>>be considered a "troll" in fact.  As it attacks a legitimate point in a
>>>>>>>>utterly simplistic and wrong context...
>>>>>>>>
>>>>>>>>Perhaps you should follow your own advice and try to be more thoughtful.
>>>>>>>>_prior_ to posting???
>>>>>>>
>>>>>>>I did. You didn't...again.
>>>>>>
>>>>>>
>>>>>>
>>>>>>Bob's post (the one you originally responded to) was perfectly fine. He just
>>>>>>gave a meaningful information.
>>>>>>
>>>>>>Your posts are really borderline. I really fail to see what is the problem with
>>>>>>Bob's post.
>>>>>>
>>>>>>Please don't start a war here. There is really no point.
>>>>>>
>>>>>>
>>>>>>
>>>>>>    Christophe
>>>>>
>>>>>I asked simple questions.
>>>>>
>>>>>I got a response but not to the questions that I asked.
>>>>>
>>>>>I asked:
>>>>>1)How much speed do you earn from using hash table
>>>>>to prune the tree in the middle game relative
>>>>>to using hash tables but not using them to
>>>>>prune the tree(not how much speed
>>>>>I can get from hash tables in the middle game).
>>>>>
>>>>>2)How much rating can I expect from using
>>>>>the hash tables to prune the tree.
>>>>>
>>>>>The response that I got are:
>>>>>
>>>>>1)Using hash tables to prune the tree is very important
>>>>>in some endgames.
>>>>>
>>>>>2)Using hash tables help to get factor of more than 2
>>>>>in the middle game.
>>>>>
>>>>>Nothing of these responses answered my questions.
>>>>>
>>>>>I have no problem with not getting a reply
>>>>>because people may not know the right reply to
>>>>>my questions but I prefer to
>>>>>get replies to the questions that I ask and not to the
>>>>>questions that I did not ask.
>>>>>
>>>>>The fact that I got from Robert hyatt only
>>>>>informationa that I did not ask is the reason that
>>>>>Ricardo Gibert said that Hyatt did not follow the thread.
>>>>>
>>>>>Uri
>>>>
>>>>Uri,
>>>>
>>>>I understand your question but unfortunately I cannot give you numbers :-)
>>>>I believe that in the _middlegame_ the contribution of the hashtables as
>>>>_pruninig_ is not so big. CT says 10% and BH say 2x which sounds to much to me,
>>>>but it might depend on the program. Anyway, the biggest contribution on the
>>>>middlegame I believe comes from the move ordering. I played a little bit with
>>>>this a while ago and there are very rudimentary experiments that seems to
>>>>suggest that once you have a good ordering the pruning by the hashtable do not
>>>>seem to be huge. It is in an article by T. Marsland "Computer Chess and Search"
>>>>in the Encyclopaedia of Artificial intelligence (page 234). This article is on
>>>>the web somewhere, I remember the reference and I suggested it here in the
>>>>group. You can do a search and find it. BUT, this experiment is very old and
>>>>limited to short depth (6).
>>>>
>>>>However, the answer about how many elo points this could give you is difficult
>>>>to answer because the real strength will be shown in the endgame. The answer to
>>>>this point cannot be separated from this fact.
>>>>
>>>>My real suggestion is that you do experiments. Just can easily add the pruning
>>>>in the code with a compiler switch so you can choose to compile it with and
>>>>without. This is really easy. If you want I will be interested in comparing
>>>>several middlegame positions side by side. I have this switch in Gaviota.
>>>>
>>>>Regards,
>>>>Miguel
>>>
>>>Thanks for your reply.
>>>
>>>1)How do I add a code with compiler switch?
>>>
>>you define a variable like this:
>>
>>#define HASH_PRUNE
>>
>>and then you do
>>
>>
>>#if defined(HASH_PRUNE)
>>    code_1();
>>#else
>>    code_2();
>>#endif
>>
>>code_1() is compiled and NOT code_2(). Also valid options are
>>
>>#ifdef HASH_PRUNE
>>    code_1();
>>#else
>>    code_2();
>>#endif
>>
>>or
>>
>>#if defined(HASH_PRUNE)
>>     optional_code();
>>#endif
>>
>>When you want to inactivate HASH_PRUNE you have
>>
>>#define HASH_PRUNE
>>#undef HASH_PRUNE
>>
>>or you can comment out the line.
>>
>>/*#define HASH_PRUNE*/
>>
>>Those switches are very powerful, I suggest you get very familiar with those.
>>Generally, the variables (like HASH_PRUNE) are in a file that is *.h and
>>inserted everywhere like
>>
>>#include "switches.h"
>>
>>Then, you can change one variable in "switches.h" and the compilation of the
>>whole program is affected. You can also control the portability of your program
>>in this way. Also, when you have a portion of code that you are not sure you
>>want to include and you are testing it, a good way to is to do this
>>
>>#if 0
>>        code_1();
>>#endif
>>
>>much better than commenting it out like this
>>
>>/*
>>        code_1();
>>*/
>
>Commenting is the way that I used.
>
>Today I have a code to print the line that movei considers every time that some
>condition happens in my program(the condition is changed).
>
>I used that code often when I found some bug in my program.
>
>It is commented as
>
>/*
>code_1();
>*/
>
>If I want to print the line that my program considers I simply change it to
>
>///*
>code_1();
>//*/
>
>and compile again.
>
>I found it as more simple than deleting the comment because if I delete the
>comments I need to think where to put them again.
>
>I never used #if or #endif in my program.

  It is a good idea to use that at least in header (.h) files, to avoid problems
with nested or repeated includes. Your chess.h file should look like this:

///////////////////////////////////////////

#if !defined(CHESS_H)
#define CHESS_H

*** your declarations here ***

#endif

///////////////////////////////////////////

  This way you can #include "chess.h" several times without compile problems.

  Josť C.


[snipped]




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