go-chess-minimax, v1.3

The library that implements a chess engine based on the minimax algorithm.

Replace a hash table with an LRU cache in a transposition table implementation, reuse it between searches and refactor.

Change Log

• transposition table:
  • store transpositions in an LRU cache instead of a hash table;
  • share a transposition table between searches;
  • disable storing zero moves in a transposition table;
• refactoring.

Features

• move searcher used the negamax algorithm;
• optimizations:
  • alpha-beta pruning;
  • transposition table:
    • storing transpositions in an LRU cache;
    • hashing a transposition by its representation in Forsyth–Edwards Notation;
    • replacing same transpositions on storing in all cases;
    • sharing a transposition table between searches;
• searching termination:
  • by a deep;
  • by a time;
• position evaluation only by a material (based on an evaluation function of Claude Shannon);
• architecture features:
  • easily extensible and composable architecture of searching;
  • composable searching terminators.

Benchmarks

chessminimax.CachedSearcher:

BenchmarkCachedSearcher_1Ply-8            100000         17615 ns/op
BenchmarkCachedSearcher_2Ply-8            100000         18070 ns/op
BenchmarkCachedSearcher_3Ply-8            100000         18059 ns/op

Repository

Link: https://github.com/thewizardplusplus/go-chess-minimax/tree/v1.3.

Content: code.

License: MIT.