Arasan 16.3

[jdart]

Arasan 16.3 is available from http://www.arasanchess.org.

Changes in Arasan 16.3:
1) Generate/search discovered checks in qsearch.
2) Changes to forward pruning in qsearch: re-introduce futility +
SEE pruning in addition to filtering capture targets in movegen.
But do not prune discovered check candidates.
3) Prune some non-capture evasions in qsearch.
4) Changes to check and capture extensions.
5) Refine extension logic when null move search shows there is
a threat related to a previous move that was reduced.
6) Defer SEE pruning until a legal move has been found/searched
(fixes bugs in mate + stalemate detection).
7) Speed enhancements in SEE, pin detection, and check status
computation.
8) Changes to weak pawn and outpost scoring.
9) Cleanup code and add some extra checks in the Notation class.
10) Fix in move generator: do not repeat hash move in winning
capture phase.
11) Use shorter time check interval for very short time controls.
Convert timing code to use high-resolution timer.
12) Change formula for computing min book weight from selectivity
setting, to play a wider variety of opening moves.

This version measures about +12 ELO compared to version 16.2 in my testing (this is running bayselo against a small pool of opponents with offset 2400, your mileage may vary).

--Jon