Hello Richard:
I agree with Dann. Just to bring some numbers into the scene, perft can be useful as well as the number of unique positions. Please imagine the starting position with well-known numbers:
Code: Select all
rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
Plies Perft(Plies) Positions(Plies)
0 1 1
1 20 20
2 400 400
3 8,902 5,362
4 197,281 72,078
5 4,865,609 822,518
6 119,060,324 9,417,683
7 3,195,901,860 96,400,335
8 84,998,978,956 988,192,872
Then imagine the same with the longest loss of the side with more pawns in KQPPvKQP endgame:
https://syzygy-tables.info/?fen=8/8/P7/ ... _w_-_-_0_1
Code: Select all
8/8/P7/1q6/4P3/6Q1/p7/k4K2 w - - 0 1
Plies Perft(Plies) Positions(Plies)
0 1 1
1 5 5
2 122 122
3 2,777 2,478
4 53,927 13,905
5 1,163,367 79,735
6 23,058,437 376,367
7 489,451,797 1,353,023
8 9,984,707,331 7,135,215
The values of the KQPPvKQP endgame were calculated with
JetChess perft counter. It depends on the endgame, but
branching factors are key in the explanation. Those numbers are not meant to be understood as an axiom since usual engines do not perform brute force analysis (i.e. searching all the nodes). Engines prune but they prune in both positions and the search tree is usually narrower with less pieces on the board, hence searching deeper in the same amount of time.
Regards from Spain.
Ajedrecista.
