v22.1 [Aug 6, 2020]
- Remove potential passer scoring.
- Tighten validation of hash/killer moves.
- Fix Resign threshold option (CECP mode).
- Simplify lmp threshold computation. No longer different for PV.
- Modify formula for lmp count. Do not allow 0 as depth index.
- Increase razor margin and reduce razoring depth.
- Fixes to singular search code. Verify hash move before doing a singular search.
- If singular extension is triggered, do not compute any additional extension, or reduction.
- Implement bench command. Use bench command for PGO.
- Update test tools to use pentanomial model for SPRT.
- MultiPV bug fixes, including a fix for bad ponder move output in MultiPV mode.
- Fix accept draw logic (CECP mode).
- Do not update history on fail high of 1st quiet and low depth (idea from Ethereal).
- Fix possible crash: when iterating through the search threads,ensure any that have.
- a null "work" pointer are skipped.
- Allow ProbCut while in check, and restrict recursive Probcut.
- Optimization in seeSign() function.
- Misc. code cleanup.
v18.0.0.1 [Aug 2, 2015]
May include unspecified updates, enhancements, or bug fixes.
v14.2.2.1 [Jun 29, 2012]
Changes in Arasan14.2b (June 2012):
- Another fix for "ping" handing in engine to cure hang problems in Arasan
GUI.
- Strength reduction operates during pondering.
- The chess engine handled input from the the UI in several places
and had duplicate code for scanning input and breaking it into lines.
This is now centralized and simplifed.
- Some other code cleanup, especially conversion from C-style string
handling to C++.
- Simplified code for lazy eval. Partial (lazy) scores are no longer
cached in the scoring module (such scores were seldom used anyway).
- Outpost scores reduced.
- Tweaked threshold values for history pruning and late move pruning (due
to a bug, 14.1 actually did only late move pruning above depth = 1 ply).
- Reduced thresholds for static null pruning.
- Some changes to LMR and root move reduction logic.
- Bug fix: ensure final stage of ply 0 search window widening sets a
correct upper/lower bound.
- Improvement to logic for searching checks in q-search.
- Fix material eval adjustment for Q vs 2R.
- Support is added for varying the engine strength via UCI or Winboard
options (Arasan GUI supports this too).
- GUI bug fix: search could hang when a "Go" command is issued when it
is the user's turn to move, and the user then makes a manual move before
the search completes.
- Winboard driver fixes: pings could be processed out of order in some
cases. Also, an extra move could be sent after Winboard has send a
"resign" or "result" command.
v13.3.0.1 [Nov 18, 2011]
Changes in Arasan 13.3:
1) In Winboard mode, Arasan still accepts but does not rely on the
deprected "white" and "black" commands to keep track of the
computer's side of the game.
2) Winboard "level" command accepts time of form mm:ss and allows decimal
times.
3) More general code for trapped bishop.
4) Static null pruning is implemented.
5) Dynamic null reduction based on score (aka "smooth scaling").
6) Changes to razor & futility margins and related code.
7) Fixes to history pruning. History table is global now, not per-thread.
