Sunday, July 31, 2016

Nirvanachess 2.3 Release

What is new in this release?

  •  Evaluation tweaks
    • Improved mobility evaluation
    • Improved Passed Pawns evaluation
    • Improved Isolated Pawn values
    •  Pieces that cannot move to the opponents side of the board are penalized
    • Bishops scale off the number of blocked pawns
    • Rooks scale based off the number of pawns
    • Pieces without safe squares to move to are considered trapped
  • Speed ups
    • Added small hash for king safety
    • Added dedicated thread for UCI input
  • Endgame knowledge
    • Added some fortress detection
    • Added KPK bitbase
    • Added draw knowledge for KRPKRP
  • Bug Fixes
    •  Fixed multiple rare crashes under SMP
Overall strength gain ~30 elo after 2000 games against 2.2 at 60"+0.05"

Download:
http://www.mediafire.com/download/ldc3e25vfcryydd/Nirvanachess_2.3.rar

Wednesday, October 14, 2015

Nirvanachess 2.2 Release

What is new in this release?

  •  Tuning with Texel's tuning method
    • Improved mobility evaluation
    • Improved Passed Pawns evaluation
    • Improved Shelter and Storming pawns evaluation
    •  
  •  SPSA tuning
    • Tuned LMP
    • Tuned LMR
  • Speed ups
    • Improved move generation speed by approximately 10%
  • New Features
    • Now accepts the "movetime" command
    • Now able to handle more than 16 gb of hash
  • Bug Fixes
    • Fixed a crash that could have occurred during late game ends
    • Fixed a crash with SMP
    • Fixed node counting during SMP
    • SMP now scales well beyond 4 cores.
 Overall strength gain ~50 elo after 5000 games against 2.1c at 60"+0.05"

Download:
http://www.mediafire.com/download/hc0g330h79urej0/Nirvanachess+2.2.rar

Monday, May 4, 2015

Nirvanachess 2.1 Release

What is new in this release?

  •  Tuning with Texel's tuning method
    • Improved king safety evaluation
    • Improved threats evaluation
    • Improved mobility evaluation
  •  SPSA tuning
    • Further tuned pruning margins
  • Added singular extensions
    • Worth approximately 20 elo!
  • Bug Fixes
    • Fixed an SMP bug that would cause crashes when running more than one thread
    • Fixed another SMP bug that caused threads to not start properly
 Overall strength gain ~80 elo after 5000 games against 2.0a at 60"+0.05"

Download:
http://www.mediafire.com/download/8hslhtv0h42phbj/Nirvanachess_2.1c.rar

Wednesday, December 17, 2014

Nirvanachess 2.0

What is new in this release?


  • A complete rewrite of the engine
    • Now uses bitboards instead of a 10x12 board representation 
      • Improves the speed of the evaluation function
    • Fixed multiple bugged located in the old evaluation function's code
      • In particular backward pawns were completely incorrectly calculated
    • Improved King safety
      • Now considers safe checks against the king when calculating attacks
    • Piece threats
      • Hanging pieces are now penalized
    • Now supports multiple cores.
      • Lazy implementation threads only communicate via the hash table.
    • Approximately 100 elo stronger than version 1.8 on a single core.

Download Link:
http://www.mediafire.com/download/5004wcpixd03f5d/Nirvanachess_2.0.rar

Tuesday, August 26, 2014

Nirvanachess 1.8 Release

What is new in this release?


  • Strength Increase
    • Scores 55% against Nirvanachess 1.7!
  • Evaluation Tweaks
    • Blocked passed pawns with a friendly blocker are now not penalized as much
    • The Bishop pair is now based more than just the number of remaining pawns
      • Includes enemy major and minor pieces
    • Reverted Rook and Queen outposts
      • Testing proved this to be a regression against other opponents
    • Implemented a lazy evaluation based on material.
    • Implemented Pawn hashing as well as pawn shelter hashing.
  •  Search Tweaks
    • Reverted LMP for bad captures
      • Testing showed poor results at long time controls.
  • Transposition Table Tweaks
    •  Pv is no longer collected from the transposition table.
    • Hashing now uses a cluster of four entries like in Fruit and Stockfish
    • Hashing no longer uses an always replace scheme
      • Older entries, Lower depth entries and non-pv entries are given lower prority
        • Performs much better under high hash pressure
  •  Bug Fixes
    • Fixed a bug where under certain conditions killer moves would not be updated properly
    • Standardized pruning at root and interior nodes
    • Fixed a bug that caused all moves to be generated under certain conditions in Qsearch

Download Link:
http://www.mediafire.com/download/6b9i7eq657o6o2o/Nirvanachess_1.8.rar

Thursday, July 3, 2014

Nirvanachess 1.7 Release

What is new in this release?

Cloptimization comes to Nirvanachess!
  • Strength Increase
    • About 40 Elo stronger than Version 1.6 at long time controls (60' + 0.05')
  • Evaluation Tweaks
    • Added dangerous Queen and Rook outpost
  •  Cloptimization
    • Updated Futility Margins
    • Updated Razoring Margins
    • Updated Isolated Pawn values
    • Updated Time Management
  • Bug Fixes
    •  Fixed a bug that would cause Nirvana to crash in ~1/5000 games due to a Hash collision

Download Link:
http://www.mediafire.com/download/fd913bf28a0bw0w/Nirvanachess_1.7.rar

Friday, April 18, 2014

Nirvanachess 1.6 Release

What is new in this release?

  • Strength Increase
    • About 40 Elo stronger than Version 1.5 at long time controls (60' + 0.05')
  • Evaluation Tweaks
    • Added knowledge of  KR vs KP endings
    • Passed Pawn evaluation is smoothed out between mid and endgame.
  • Optimization
    •  Slightly quicker during the mid and end games (~2%)
  • Bug Fixes
    • Fixed a bug with pawnstorms
      • Sometimes would count pawnstorms twice
    • Fixed a bug with pawn shelter
      • Sometimes would count shelter pawns twice
    • Fixed a bug that would cause pawns to be completely mis-evaluated.

Download Link:
http://www.mediafire.com/download/fcdz82s1g2tr9lp/Nirvanachess1.6.rar