An Evaluation Hash Table may be used in a similar fashion as a transposition table, that is using Zobrist or BCH hashing, to cache various computational expensive positional evaluation scores and flags.

• Despite the fact that the transposition table entries may contain evaluation scores as well, a tighter, dedicated evaluation hash table with its own replacement policy may gain a considerable amount of additional hits.

What sizes should these have?

• The UCI protocol comes with a command where the hash size can be set.

Since the pawn structure changes very rarely it should be a nice boost as long as it gets implemented smoothly.

Needs to store information about passed pawns so we do not have to find them every time.