Plausibility based extension/reduction

[sje]

Plausibility based extension/reduction

Back in the 1960s, Richard Greenblatt and some of his colleagues wrote Mac Hack VI, a Shannon type B chess playing program. Mac Hack used about fifty plausibility heuristics for selecting and ordering the best N moves at a node to be chosen for further examination.

Some of these heuristics were path dependent. For example, the program assigned higher plausibility to moves of pieces that had not moved two ply earlier.

My idea is to use path dependent heuristics to assist with search depth extension and reduction management.

For example:

1) Moving the same piece back to its immediately prior square -> reduce

2) Moving the same sweeper (BRQ) piece twice in a row in the same direction -> reduce

[Teemu Pudas]

For example:

1) Moving the same piece back to its immediately prior square -> reduce

2) Moving the same sweeper (BRQ) piece twice in a row in the same direction -> reduce

Either of those in response to a nullmove -> prune.

[Gerd Isenberg]

Plausibility based extension/reduction

Back in the 1960s, Richard Greenblatt and some of his colleagues wrote Mac Hack VI, a Shannon type B chess playing program. Mac Hack used about fifty plausibility heuristics for selecting and ordering the best N moves at a node to be chosen for further examination.

Some of these heuristics were path dependent. For example, the program assigned higher plausibility to moves of pieces that had not moved two ply earlier.

My idea is to use path dependent heuristics to assist with search depth extension and reduction management.

For example:

1) Moving the same piece back to its immediately prior square -> reduce

2) Moving the same sweeper (BRQ) piece twice in a row in the same direction -> reduce

If a repetition is the best you can get, 1) should not reduced let say directly into qsearch to eventually miss the (forced) repetition. Also, if after move(A)-move(B, attacking the to-square of move(A)) moving back is forced, but the whole maneuver has weakened let say the pawn structure. For 2) there are exceptions as well, for instance if the sweeper was forced to move twice, because it got attacked.