Skip to content

Bread Engine 1.5.0

Choose a tag to compare

View all tags
@Nonlinear2 Nonlinear2 released this 13 Jul 08:58
· 398 commits to main since this release
v1.5.0
183d038

Bread Engine 1.5.0 is around 124 elo stronger than version 1.4.0 in STC and around 167 elo stronger in LTC.

These gains mainly come from new heuristics, better histories and bugfixes. The nodes per second in the bench command can no longer be negative (oops), and there sould be no more illegal pv lines.
The executable is also roughly two times smaller as the neural network weights are now embedded in their quantized integer type.

Additions/Improvements:

  • improve late move reductions (~10 elo)
  • switch to a quadratic razoring threshold (~16 elo)
  • refactor and improve root move ordering (~13 elo)
  • use static exchange evaluation in move ordering (~47 elo)
  • use an assembly incbin macro to embed the neural network in the executable
  • add and improve continuation history (~27 elo)
  • add singular extensions (~14 elo)

Bug fixes:

  • fixed reporting illegal pv moves when the game ends in a draw
  • fixed a bug with quiescence search transposition evaluations
  • fixed an integer overflow when displaying the nodes per seconds in bench
  • fixed the quiet history being used only for one side (~53 elo)

Of course adding up the elo estimates of each improvement doesn't match the overall gain, as life would be too good otherwise.

In addition, major refactors and readability improvements have been done in the move ordering, root search, nnue and search parts of Bread.

STC: 8 + 0.08 s

Results of bread_engine_1.5.0 vs bread_engine_1.4.0 (8+0.08, NULL, NULL, UHO_2024_8mvs_big_+115_+134.pgn):
Elo: 123.55 +/- 14.22, nElo: 166.12 +/- 17.58
LOS: 100.00 %, DrawRatio: 32.67 %, PairsRatio: 5.39
Games: 1500, Wins: 817, Losses: 305, Draws: 378, Points: 1006.0 (67.07 %)
Ptnml(0-2): [19, 60, 245, 242, 184], WL/DD Ratio: 5.45

LTC: 40 + 0.4 s

Results of bread_engine_1.5.0 vs bread_engine_1.4.0 (40+0.4, NULL, NULL, UHO_2024_8mvs_big_+115_+134.pgn):
Elo: 167.53 +/- 21.02, nElo: 230.86 +/- 24.87
LOS: 100.00 %, DrawRatio: 25.60 %, PairsRatio: 8.30
Games: 750, Wins: 433, Losses: 97, Draws: 220, Points: 543.0 (72.40 %)
Ptnml(0-2): [2, 28, 96, 130, 119], WL/DD Ratio: 2.10
Assets 3
Loading