Author: Christophe Theron
Date: 19:56:04 04/08/99
Go up one level in this thread
On April 08, 1999 at 17:27:33, Roberto Waldteufel wrote:
>On April 08, 1999 at 16:37:52, Christophe Theron wrote:
>
>>On April 08, 1999 at 13:44:11, Roberto Waldteufel wrote:
>>
>>>By a threat for the other side, I mean that, if it were in fact the other side's
>>>turn to play, he would have a capture. Therefore threats by side to move would
>>>mean that the side to move has one or more legal captures available, which is
>>>precisely the condition I started out with to trigger an extension. The
>>>enhancement was to extend if *either side* has pending captures.
>>
>>OK, I thought at first it was asymetric.
>>
>>
>>>The whole
>>>qseearch is easier than in chess precisely because of the obligation to capture
>>>whenever possible - it is not really a qsearch in the sense we use that term for
>>>chess
>>
>>It is the same than in chess from my point of view. QSearch is: "don't stop
>>while something is happening". The difference is how you judge that something is
>>happening... Even in chess you can think of different ways to implement a
>>QSearch, isn't it?
>>
>
>Yes, exactly so. It is only how I define "something is happening" that is a
>little bit different because of the different rules of checkers (as compared to
>chess) when captures are possible.
It's interesting to find general concepts that can be applied to different
games, or a concept general enough to be implemented in several ways for a
single game. Then you can play and experiment with it.
I'm wondering if the concept of QSearch (as defined above) applies to
Othello/Reversi too?
Are you doing extensions in checkers as we do in chess? Do they use extensions
in Reversi?
>I think if I tried to implement the exact
>same method in chess, my Qsearch would explode and the search would never
>terminate.
That's indeed the problem.
Christophe
>>>- rather it is an extension of the full width search. The only cases that
>>>escape this technique are so called "pitch" moves, where neither side has a
>>>capture, but the side to move deliberately offers a sacrifice of a piece (which
>>>must be accepted because of the obligation to capture whenever possible) in such
>>>a position that the material scrificed can either be regained with interest or
>>>an overwhelming positional superiority can be established by means of the
>>>sacrifice.
>>>
>>>If you ever turn your hand to another game, I can highly recommend checkers. It
>>>has far more depth and subtlety than I ever thought possible with such a limited
>>>set of moves compared to chess. The late Dr Marion Tinsley, thought by many to
>>>be the best (human) player of all time, was also quite a strong chess player in
>>>his youth. He compared the two games nicely thus: "Chess is like looking out
>>>over a limitless ocean, whereas checkers is like looking down a bottomless
>>>well".
>>
>>I understand...
>>
>>
>> Christophe
>>
>>
>>>I understand from that quote that in checkers, because of the lower
>>>branching factor, you can look further ahead, but still sooner or later you must
>>>reach a horizon where a (possibly erroneous) positional evaluation must be made,
>>>just as happens in chess and other games. In my experience it is often more
>>>difficult to describe accurately what constitutes a positional advantage in
>>>checkers than it is in chess, although that might be because I am not very
>>>experienced at checkers, whereas I have played, studied and programmed
>>>competitive chess for many years.
>>>
>>>Best wishes,
>>>Roberto
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.