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Revisiting Check Extensions
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José C. Martínez Galán



Joined: 08 Mar 2006
Posts: 147
Location: Murcia (Spain)
PostPost subject: Re: Revisiting Check Extensions    Posted: Thu Jun 07, 2007 11:01 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


I think, but I haven't tested it, that the logic of extensions is to find that a special move changes the score of the line from fail low to fail high. Checks have the chance to convert a fail low (for example down in material) to a fail high (f.e. draw by repetition). Then if you're up in material and expect a fail high, search to normal depth and find a fh, you have no need to extend. However, if you fail low when you expected to fail high, then it makes sense to extend just in case the check might raise the score.
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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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