Indeterminate starting chess positions

[Programmist]

In the general opinion of many chess analysts, classic chess starting position is drawish with a large margin, moreover, results of high level correspondence chess tournaments prove it. The question arises, does every initial starting position have a clear assessment? And what makes the classic position drawish?

Experimental games and some theory show, that positions with different arrangement of black and white pieces are less definite.

In such positions, one side is often stronger and fights for win, while other side tries to defend. This makes chess game with this starting position a two result game effectively in advanced chess.

Initial position name AlfaDelta-

brnqknrb/pppppppp/8/8/8/8/PPPPPPPP/RKBNQBNR w - - 0 1
Score 3-3 by advanced chess games with long time control


Initial position name EtaAlfa-

rnbqnbkr/pppppppp/8/8/8/8/PPPPPPPP/RNBKNBQR w - - 0 1
(black to win)

Score 4-5 by advanced chess games with long time control


Initial position name BetaZeta+

bnrkqrnb/pppppppp/8/8/8/8/PPPPPPPP/RKBNNBQR w - - 0 1
Score 2-2 by advanced chess games with long time control


Initial position name GammaZeta+

bnrkqrnb/pppppppp/8/8/8/8/PPPPPPPP/RKNBBNQR w - - 0 1
Score 1-3 by advanced chess games with long time control


Initial position name BetaZeta-

bnrqkrnb/pppppppp/8/8/8/8/PPPPPPPP/RKBNNBQR w - - 0 1
Score 2-4 by advanced chess games with long time control


Initial position name GammaZeta-

bnrqkrnb/pppppppp/8/8/8/8/PPPPPPPP/RKNBBNQR w - - 0 1
Score 3-2 by advanced chess games with long time control


Arrangements of white and black pieces were selected among symmetrical ones.

[Programmist]

ASFC (chess with indefinite starting positions) engine tournament. Time control 180 minutes + 20 seconds per move.

Code: Select all

Stockfish 8.9   | *  | 11 | 11 | 11 | 33 | +9 | 69% | 1 
Stockfish 8     | 5  | *  | 10 | 11 | 26 | +2 | 54% | 2  
Strong Engine Y | 5  | 6  | *  | 9  | 20 | -4 | 42% | 3 
Strong Engine X | 5  | 5  | 7  | *  | 17 | -7 | 35% | 4

No draws, score 45-51 for defending side. Stockfish 8.9 is last Stockfish build. With undetermined starting positions difference between stronger and weaker engines is much bigger, cause drawish nature of usual positions does not affect and diminish engine's advantages.