theoretical draws

[brtzsnr]

Are the following positions theoretical draws? Should zurichess return a move here? According to [1] they are and the game should be adjourned (FIDE Laws of Chess, article 9.6). However, cutechess doesn't detect them as draws and complains when zurichess doesn't return a move.

[d] 3K4/1b6/8/kB5B/8/8/8/8 w - - 0 1

[d] B7/8/8/3K3B/8/8/7k/5b2 w - - 1 2

[d] 8/4BK2/2k5/8/1B6/8/8/8 b - - 0 2


[1] http://www.e4ec.org/immr.html

[Sven]

Are the following positions theoretical draws? Should zurichess return a move here? According to [1] they are and the game should be adjourned (FIDE Laws of Chess, article 9.6). However, cutechess doesn't detect them as draws and complains when zurichess doesn't return a move.

Yes, all of these positions are draws, not just "theoretical draw" but even draw by FIDE rules. There is no sequence of legal moves for either side to checkmate the opponent when both sides only have the king and zero or more bishops, and all bishops on the board reside on squares of the same color.

[brtzsnr]

Ok. Filled a bug with cutechess. Will amend my engine to keep searching at root when the position is drawn.

[Sven]

[d]1k2B3/3b1B2/1KB1b1B1/3B1b1B/2b1B1b1/3b1B1b/4b1B1/5b2 w - - 0 1
Can white win material?

[Dann Corbit]

Why not:
[d]1k2B3/3b1B2/1KB1b1B1/1b1B1b1B/2b1B1b1/3b1B1b/4b1B1/5b1B w - -

[kbhearn]

10 light bishops is an illegal position

[hgm]

This is a forced win, however:
[d]1b1b1b1b/b1b1b1b1/1b1b1b1b/b1bkb1b1/1b1b1b1b/b1bKb1b1/1b1bBb1b/b1b1b1b1 w

Note that WinBoard/XBoard would adjudicate the menitioned KBBKB correctly.

[brtzsnr]

This is a forced win, however:
[d]1b1b1b1b/b1b1b1b1/1b1b1b1b/b1bkb1b1/1b1b1b1b/b1bKb1b1/1b1bBb1b/b1b1b1b1 w

Note that WinBoard/XBoard would adjudicate the menitioned KBBKB correctly.

In order to adjudicate, all bishops must be on the same color. Here the white bishop is on white, and black bishops are on white.

[pkumar]

e2g4 d5c6 d3c4 c6b7 c4b5 b7a8 g4f3+

Quite a few engines crash, a few others see only draw.

[Sven]

10 light bishops is an illegal position

Not illegal but unreachable from the starting position ... Therefore few GUIs (including CB) do not allow to enter such a position graphically.