Puffin 4.0

All-around improvements that hopefully lead to a decent gain in strength. I expect (hope?) that the strength is now around 2900 Elo, roughly a 150 Elo gain (relative to the CCRL ratings list).

Some, but not all, of the changes:

• Better time management
• Added countermove heuristic
• Added SEE pruning to main and quiescent searches
• Tweaks to existing pruning techniques
• Added bishop pair eval term to evaluation
• Added rook on open file eval term
• Improvements to existing evaluation items
• Validate hash move before attempting to play it
• Better thread management

Self-play vs Puffin 3.0

Score of Puffin 4.0 vs Puffin 3.0: 113 - 8 - 44  [0.818] 165
...      Puffin 4.0 playing White: 54 - 5 - 24  [0.795] 83
...      Puffin 4.0 playing Black: 59 - 3 - 20  [0.841] 82
...      White vs Black: 57 - 64 - 44  [0.479] 165
Elo difference: 261.3 +/- 51.8, LOS: 100.0 %, DrawRatio: 26.7 %
SPRT: llr 2.95 (100.3%), lbound -2.94, ubound 2.94 - H1 was accepted

Bullet (10s+0.1) Gauntlet

   # PLAYER         :  RATING  ERROR  POINTS  PLAYED     W     D     L  D(%)
   1 frozenight     :  3125.0   ----   513.5     600   465    97    38    16
   2 avalanche      :  2880.3   34.4   357.0     600   273   168   159    28
   3 halogen        :  2843.3   34.2   326.0     600   260   132   208    22
   4 leorik         :  2838.0   34.6   321.5     600   248   147   205    25
   5 Puffin 4.0     :  2812.9   28.1  2576.0    4800  2027  1098  1675    23
   6 Lynx           :  2720.2   34.7   222.5     600   131   183   286    31
   7 princhess      :  2707.6   35.5   212.5     600   164    97   339    16
   8 peacekeeper    :  2622.7   36.8   151.5     600    97   109   394    18
   9 Puffin 3.0     :  2569.0   37.4   119.5     600    37   165   398    28

Puffin 3.0

This is a smaller release that brings a small gain in playing strength.

A bug with detecting 3-fold repetition properly was hopefully fixed.

Added features:

• late move pruning
• internal iterative reduction
• isolated pawn eval
• draw detection for 50 moves and material draws

Self-play vs Puffin 2.0

Score of puffinnew vs puffinold: 237 - 122 - 288  [0.589] 647
...      puffinnew playing White: 119 - 59 - 146  [0.593] 324
...      puffinnew playing Black: 118 - 63 - 142  [0.585] 323
...      White vs Black: 182 - 177 - 288  [0.504] 647
Elo difference: 62.4 +/- 20.0, LOS: 100.0 %, DrawRatio: 44.5 %
SPRT: llr 2.96 (100.6%), lbound -2.94, ubound 2.94 - H1 was accepted
Finished match

Bullet (10s+0.1) Gauntlet

 #  PLAYER           :  RATING  ERROR  POINTS  PLAYED     W     D     L  D(%)
 1 Nalwald 15        :  2912.0   ----   465.0     600   418    94    88    16
 2 Frozenight 3.0.0  :  2883.9   32.8   447.5     600   371   153    76    26
 3 Leorik 2.4        :  2824.0   31.4   405.5     600   329   153   118    26
 4 Halogen 8         :  2772.4   31.3   365.0     600   310   110   180    18
 5 Apotheosis 4.0.1  :  2709.3   30.4   312.0     600   223   178   199    30
 6 Peacekeeper 1.40  :  2695.8   30.9   300.5     600   235   131   234    22
 7 Puffin 3.0        :  2695.3   23.4  2326.5    5400  1671  1311  2418    24
 8 Princhess 0.12.0  :  2671.9   31.0   280.0     600   241    78   281    13
 9 Lynx 1.3          :  2635.7   30.3   249.5     600   169   161   270    27
10 Puffin 2.0        :  2634.5   30.7   248.5     600   122   253   225    42

Puffin 2.0

Puffin 2.0 brings mostly improvements rather than additional new features (though there are some). I'm expecting/hoping for roughly a 120-150 Elo boost in strength.

Some of the changes in this release include:

• Upgrade to .NET 8
• Fixed some issues with the evaluation tuner
• Some new pawn evaluation terms:
  • passed pawns
  • defended pawn (by another pawn)
  • adjacent/connected pawns
  • king distance for passed pawns
• A fix to repetition detection
• Some additional features in the quiescence search:
  • delta pruning
  • save/probe transposition table in qsearch

Self-play vs Puffin 1.0

Score of Puffin-2.0 vs Puffin-1.0: 218 - 70 - 93  [0.694] 381
...      Puffin-2.0 playing White: 114 - 34 - 43  [0.709] 191
...      Puffin-2.0 playing Black: 104 - 36 - 50  [0.679] 190
...      White vs Black: 150 - 138 - 93  [0.516] 381
Elo difference: 142.4 +/- 32.0, LOS: 100.0 %, DrawRatio: 24.4 %
SPRT: llr 2.95 (100.3%), lbound -2.94, ubound 2.94 - H1 was accepted
Finished match

Bullet (10s+0.1) Gauntlet

 # PLAYER               :  RATING  ERROR  POINTS  PLAYED     W     D     L  D(%)
 1 Frozenight 3.0.0     :  2904.0   ----   478.5     600   423   111    66    19
 2 Leorik 2.2           :  2716.8   31.6   345.0     600   246   198   156    33
 3 Apotheosis 4.0.1     :  2684.8   31.3   318.0     600   238   160   202    27
 4 Peacekeeper 1.40     :  2678.4   32.0   312.5     600   236   153   211    26
 5 Puffin 2.0           :  2663.8   24.7  2889.5    5400  2291  1197  1912    22
 6 Princhess 0.11.0     :  2642.1   31.9   281.5     600   235    93   272    16
 7 Pedantic 0.3.1       :  2628.6   31.8   270.0     600   214   112   274    19
 8 Halogen 7            :  2557.9   32.5   212.0     600   156   112   332    19
 9 Puffin 1.0           :  2511.8   32.7   177.5     600   102   151   347    25
10 Lynx 1.0.1           :  2412.5   34.9   115.5     600    62   107   431    18

Puffin 1.0.0

The first release! If you are unsure of which executable to use, please see the readme (or just try Puffin.exe first).

Features

Search:

• NegaScout
• Iterative deepening
• Aspiration window
• Quiescence
• Staged move generation
• Late move reductions
• Null move pruning
• Futility pruning
• Reverse futility pruning
• Transposition table (always replace scheme)
• Multithreading (Lazy SMP)

Evaluation:

• Piece square tables
• Mobility
• King safety