/*

Pseudocode for Cutoff Checks

Copyright 2017 Tom Kerrigan

There are notes at the end of this file.

*/

#define CUTOFF_CHECK_DEPTH    4

int search(int alpha, int beta, int depth)

{

    ...

    // normal hash table probe

    x = probe_hash_table(hash_key, alpha, beta, depth);

    if (x != KEEP_SEARCHING)

        return x;

    generate_moves();

    for (i = 0; i < moves; i++)

        {

        if (deferred_moves != 0 &&              // note 1

                depth >= CUTOFF_CHECK_DEPTH)    // note 2

            {

            // cutoff check

            x = probe_hash_table(hash_key, alpha, beta, depth);

            if (x != KEEP_SEARCHING)

                return x;

            }

        make_move(move[i]);

        ...

/*

Note 1:

If there aren't any deferred moves, it's impossible that a deferred move would have failed high.

Note 2:

CUTOFF_CHECK_DEPTH reduces memory traffic by preventing cutoff checks at shallow depths.

VERSION HISTORY

Version 1.0, 8/24/17

- First version

*/