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Revisiting Check Extensions
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Uri Blass



Joined: 08 Mar 2006
Posts: 5958
Location: Tel-Aviv Israel
PostPost subject: Re: Revisiting Check Extensions    Posted: Thu Jun 07, 2007 10:59 am Reply to topic Reply with quote
Tord Romstad wrote:
Uri Blass wrote:
I do not extend checks when the side that gives the check had a big material advantage before giving the check.

Hello Uri,

Are you sure this really works? It looks very dangerous to me: I would expect serious horizon effect problems. One of the main reasons why check extensions work is that in positions where you are faced with some threat against which there is no defence, a check can often postpone the inevitable by one ply. You can easily find many examples of this, for instance positions with a deadly fork or pin, or endgames with a rook against a pair of advanced passed pawns, where the rook cannot stop the pawns, but can give several checks before the pawns can promote.

Mark's scheme looks more promising to me.

Tord


Note that big material advantage for me is defined as at least 8 pawns

Practically to be more correct it is big evaluation advantage of at least 8 pawns(I evaluate every node)

positions when the side that gives check postpone the inevitable by one ply with that advantage are rare and I believe that it helps.


Note that I did not test it seriously to be sure that it helps

The idea is that you do not want to extend checks when you feel sure about the expected result.

limit_check 800 is the default personality.

It is possible to change the constant of 8 pawns to a bigger constant or smaller constant by changing personality of movei but I did not do it.
If people are interested in testing it then you should only add
limit_check 400 in a personality file to see if not extending when the advantage is 4 pawns is better.

Uri

Last edited by Uri Blass on Thu Jun 07, 2007 11:01 am; edited 1 time in total
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Display posts from previous:   
Subject Author Date/Time
Revisiting Check Extensions Mark Lefler Thu Jun 07, 2007 9:25 am
      Re: Revisiting Check Extensions Uri Blass Thu Jun 07, 2007 10:19 am
            Re: Revisiting Check Extensions Tord Romstad Thu Jun 07, 2007 10:33 am
                  Re: Revisiting Check Extensions Uri Blass Thu Jun 07, 2007 10:59 am
                        Re: Revisiting Check Extensions Uri Blass Fri Jun 08, 2007 8:37 am
                              Re: Revisiting Check Extensions ed Fri Jun 08, 2007 9:40 am
                                    Re: Revisiting Check Extensions Uri Blass Fri Jun 08, 2007 10:06 am
                  Re: Revisiting Check Extensions José C. Martínez Galán Thu Jun 07, 2007 11:01 am
                  Re: Revisiting Check Extensions H.G.Muller Thu Jun 07, 2007 11:59 am
            Re: Revisiting Check Extensions Mark Lefler Thu Jun 07, 2007 1:05 pm
      Re: Revisiting Check Extensions Robert Hyatt Fri Jun 08, 2007 3:25 pm
            Re: Revisiting Check Extensions Tony Fri Jun 08, 2007 3:50 pm
                  Re: Revisiting Check Extensions Robert Hyatt Fri Jun 08, 2007 4:03 pm
                        Re: Revisiting Check Extensions Tony Fri Jun 08, 2007 7:28 pm
            Re: Revisiting Check Extensions Mark Lefler Sat Jun 09, 2007 8:04 pm
                  Re: Revisiting Check Extensions Robert Hyatt Sat Jun 09, 2007 9:59 pm
                        Re: Revisiting Check Extensions Mark Lefler Sun Jun 10, 2007 7:34 am
                              Re: Revisiting Check Extensions Uri Blass Sun Jun 10, 2007 7:46 am
                              Re: Revisiting Check Extensions Robert Hyatt Sun Jun 10, 2007 3:25 pm
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