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Subject: Rebel and Move Ordering

Author: Howard Exner

Date: 15:44:39 11/17/97


This is problem # 21 from BT2630
k7/8/PP1b2P1/K2Pn2P/4R3/8/6np/8 w - - id"Bt21 - Re4-e1";

Here is Rebel 8's analysis of this position (K6-233;60 MB hash)

Move	Time	Ply	Eval

g6-g7	0:01	7	+2.68
"	0:03	8	+2.68
"	0:12	9	+1.48
"	0:33	10	+2.17
"	1:01	11	+2.17
"	2:41	12	+2:09
"	24:06	13	+0.23

Now Rebel 8 ponders the move b6-b7+ for ~25 minutes.

Re4-e1	55:59	13.09	+2.06

My question is about the ordering of moves. For this position
Rebel 8 orders the move b6-b7+ as the second best. I did a quick
"power analysis" (this is a Rebel 8 feature) on the move b6-b7
and then on Re4-e1. Here is what Rebel 8 finds in "power analysis"
mode.

Ply	Eval	Eval
	b6-b7	Re4-e1

7	-1.53	-1.41
8	-2.81	-0.36
9	-2.48	-0.42
10	-5.95	-0.80
11	-6.98	+0.96

Why doesn't Rebel 8 order the move Re4-e1 before
b6-b7 since it discovers rather quickly that Re4-e1
is much better? Would it not be useful to re-order
the moves after each ply? What are the obstacles in
doing this?

Chris W, from another post, sparked my curiousity to look at this
position.



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