Arasan 21.2

[jdart]

Arasan 21.2 is available from https://www.arasanchess.org.

Changes in Arasan 21.2:
1) Add support for >64 cores.
2) Rework NUMA support to use hwloc 2.x API. Add code to handle Windows
processor groups (not really tested at present).
3) Bug fix: don't access counter move arrays when previous move was null.
4) Fix bug in thread usage reporting.
5) Bug fix: beta could be outside MATE score range during singular search.
6) Don't do check extension if outside late move pruning limit (like
Stockfish).
7) Make LMP dependent on improving flag.
8) Set contempt based on ratings with sigmoid function: avoids
excessively large contempt values.
9) Improvements in time management.
10) Fixes in Winboard protocol.
11) Suppress trace information from the polling thread: fixes issues when
running with trace flag (-t) on.
12) Fix thread selection logic at end of search so that main search is not
selected if it does not have a PV.
13) Add some scoring for pawn storms (pawn advances near opposing
king).
14) Changes to "lazy SMP" thread depth distribution.
15) Fix node count & time reporting for "test" command.

I am including NUMA-enabled binaries for Windows and Linux. These have only been lightly tested, however, and not on super-high core count machines. These binaries depend on the hwloc library: a DLL is included in the Arasan engine package for Windows.

Overall I expect this version to be only moderately stronger than 21.1, but it has a number of significant fixes.

--Jon

[Werner]

Thanks Jon,
...15 changes and only moderate stronger ? I hope for more than 15 Points

I wish you all the best for 2019 and hope for an Arasan > 3000 Points in our list.