Author: Christophe Theron
Date: 12:20:40 07/21/02
Go up one level in this thread
On July 20, 2002 at 22:27:26, Robert Hyatt wrote:
>On July 20, 2002 at 16:21:10, Christophe Theron wrote:
>
>>On July 20, 2002 at 16:02:54, Ricardo Gibert 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'm perplexed as to why you would take RHs side in this. My post was pretty mild
>>>compared to some of the others that get posted here without rebuke from a
>>>moderator including some of your own posts. I can only conclude that it is due
>>>to RH's status in this forum. So be it. I will make no further posts in this
>>>thread.
>>
>>
>>
>>No it's just that I see that this is going to degenerate pretty quickly into
>>name-calling due to Bob's nature and your -in my opinion- unjustified comment.
>>
>>Yes your comment was mild, but it was not justified (again, in my opinion). I
>>know Bob is going to react very harshly, and before he does I prefer to ask the
>>one who was wrong (you, in my opinion) to reconsider.
>>
>>If I don't act immediately I will have to moderate Bob, and I'm not sure what is
>>going to happen then. :)
>>
>>
>>
>> Christophe
>
>
>Doesn't bother me at all to be moderated, as a general rule. I've said all I
>intend to say anyway. No idea why he reacted as he did. No idea how he missed
>the point I tried to make. But it isn't that important. The rest seemed to
>"get it" ok..
OK, no problem. :)
Christophe
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