Computer Chess Club Archives




Subject: Measured min-max branching factor

Author: James Swafford

Date: 04:58:00 10/17/02

I did this test because I've always heard "35 or 36" as the
accepted bf when doing a min-max search, and Vincent has been
claiming that it's more like 40.

Test 1: WAC1-100 (10 sec/mv) ==> avg bf = 34.29
Test 2: ECM98    (10 sec/mv) ==> avg bf = 36.85

So, I'll stick with "35 or 36".

Ok, a few details.  No qsearch, no null, no pruning of any kind,
no hashing.  Alpha was set to -inf and beta to +inf upon entry
to the search.

I measure bf after each completed iteration simply by doing:
  bf[iteration] = nodes[iteration] / nodes[iteration-1];

After each problem, I compute the average of the bf's for each
completed iteration.  After the entire suite, I use the average
of the averages as the final bf.


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