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Subject: Singular extensions exact?

Author: Bas Hamstra

Date: 08:26:20 01/09/98


Bob and Don thanks.

I hope you don't mind I have more to ask about singular extensions.

So the basic idea is to grant an extension if one move is much better
than the rest, to follow forced lines, much like it is done
with checks. But checks are *absolutely* forcing, while singular moves
are not....

Example: you are at D=9 and find a singular move. Any other move loses a
pawn, so extend. In fact you discard other moves. But maybe that is NOT
correct! Maybe if you would search to D=13 you would find that one of
the moves you discarded wins a piece!! So how reliable are the forced
lines you build? A specific question:

Suppose a 9 ply search leads to a 17 ply forcing line with score
+3 pawns. Is it a garantueed 17 ply score then? No 17 ply brute force
search could ever prove the score being less?

That's what I keep thinking about. And I have the feeling the answer is
NO, a 17 ply BF search could still prove it being false (very much
unlike chess extensions I would think), because moves have been
discarded on the basis of a 9 ply search. Of course it could still
"work", but as no more than an inexact  selection heuristic.

Comments?

The second question is: has it been tried to steer the game into a
direction where the opponent has lesser choices?



Regards,

Bas Hamstra.



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