Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: Qsearch Checks

Author: Stuart Cracraft

Date: 19:14:26 09/05/04

Go up one level in this thread


On September 05, 2004 at 19:34:21, Uri Blass wrote:

>On September 05, 2004 at 19:14:30, Stuart Cracraft wrote:
>
>>On September 05, 2004 at 18:30:30, Bas Hamstra wrote:
>>
>>>On September 05, 2004 at 17:02:49, Uri Blass wrote:
>>>
>>>>On September 05, 2004 at 16:37:32, Stuart Cracraft wrote:
>>>>
>>>>>On September 05, 2004 at 15:58:39, Bas Hamstra wrote:
>>>>>
>>>>>>On September 05, 2004 at 14:56:14, Uri Blass wrote:
>>>>>>
>>>>>>>On September 05, 2004 at 14:30:01, Bas Hamstra wrote:
>>>>>>>
>>>>>>>>>My program has this in relation to checks, all conditionally compilable:
>>>>>>>>>
>>>>>>>>>  1) all checks-evasions in quiescence, unlimited occurrences
>>>>>>>>>  2) all checks-evasions in main search, unlimited occurrences
>>>>>>>>>  3) all checking-moves in quiescence, at the first ply of quiescence
>>>>>>>>>
>>>>>>>>>These are the three extensions. Only #1 and #2 have proved useful.
>>>>>>>>
>>>>>>>>Impossible. When I did 3) it solved wac141 within one second, using a mate
>>>>>>>>extension of a full ply. It takes 30.000 nodes and 6 plies to anounce M6.
>>>>>>>
>>>>>>>With mate extension of a full ply your search will explode because
>>>>>>>there are positions when there are a lot of checks and every reply to check is
>>>>>>>a mate threat.
>>>>>>
>>>>>>Not in my search. But I have taken actions to prevent "stapling" of useless
>>>>>>matethreats. I have done a full ply mate-extend in Tao 5.4 without problems.
>>>>>>
>>>>>>>6 plies to see the mate and only 30000 nodes.
>>>>>>>It seems to me hard to believe it espacially when I expect your search with
>>>>>>>full ply extension for mate to explode.
>>>>>>
>>>>>>See above for the explosion. I am not saying a full ply mate-ext is best, but I
>>>>>>have used it for years and it worked fine. This is probably also a matter of
>>>>>>what your qsearch can do. Mine can solve simple multi-move mates.
>>>>>>
>>>>>>>Of course checks in the qsearch helps but I still need 8 plies without mate
>>>>>>>extensions only to find the move without mate score(it is after I decided to
>>>>>>>reduce my evaluation based pruning).
>>>>>>
>>>>>>Yes, I checked and have the same result without mate-ext.
>>>>>>
>>>>>>>I will check with enabling mate extensions only in the first 11 plies(no need
>>>>>>>to extend after 11 plies to find mate in 6) and check results again.
>>>>>>>
>>>>>>>>Without it it has a hard time and it takes very long. The point is: if your
>>>>>>>>qsearch cannot find a simple mate in one (a capture only qsearch wont) chances
>>>>>>>>are you will find this mate a full 3 plies later than necessary.
>>>>>>>>
>>>>>>>>If you implemented 3) your program should mate-extend like crazy here...
>>>>>>>>
>>>>>>>>Bas.
>>>>>>>
>>>>>>>If he implements 3 then his program will crash because it will never get to the
>>>>>>>second ply of the qsearch because his qsearch call the main search and not the
>>>>>>>qsearch.
>>>>>>
>>>>>>You are right here. When you do checks on the first q-ply and call the mean
>>>>>>search for check-evasions, you will have unlimited checking sequences and that's
>>>>>>bad.
>>>>>>
>>>>>>Bas.
>>>>>
>>>>>Repetition detection would take care of that.
>>>>>
>>>>>My search terminates and never goes anywhere near the 99 maximum ply
>>>>>setting. Usually at 8, 9, 10, 11 ply it is no more than 4x the nominal
>>>>>main search depth, e.g. 32, 36, 40, 41 -- I don't limit quiescence to
>>>>>that, it just often turns out that way.
>>>>>
>>>>>No unlimited checking sequences noted due to repetition detection and
>>>>>draw return in both mainsearch and quiescence.
>>>>>
>>>>>On the other hand, I am anxious to try a quiescence that does not
>>>>>handoff to main search to get out of check in quiescence. I was hoping
>>>>>to do that this afternoon.
>>>>>
>>>>>Stuart
>>>>
>>>>I guess that you did not search the right positions or did not search deep
>>>>enough to get the 99 plies
>>>>
>>>>there are positions when there can be easily more than 99 plies of checks with
>>>>no repetition.
>>>>
>>>>Uri
>>>
>>>
>>>I have the same experience.
>>>
>>>Bas.
>>
>>Most programs I've heard of have a maximum ply setting beyond which the
>>search can't go.
>>
>>How about you Uri and you Bas?
>>
>>Stuart
>
>Movei assumes that the ply is always smaller than 100
>If it is bigger than 100 the program may crash because it does not check if
>ply<100 in it's search.
>
>Practically based on my experience it never get close to 100.
>
>Uri

Well, this is what I have observed with my program allbeit on slow
hardware and with extremely short searches.

However, I do occasionally feed it the various challenge positions
posted by posters on this board and let it run for a few minutes.

Usually, 40 or 50 ply is the max ever reached.

There is probably a good reason to limit this as out that far it
looks rather outlandish.

Stuart




This page took 0 seconds to execute

Last modified: Thu, 15 Apr 21 08:11:13 -0700

Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.