[Retros] Solidarity chess (=SC)

Nicolas Dupont Nicolas.Dupont at univ-lille1.fr
Thu Dec 20 11:46:51 EST 2012

Noam said:

> No real difference as long as you're concerned only with orthodox play

> (wins stay wins, "mate in n" becomes "win in n+1", etc.). But in

> help-play (including "proof games") it is crucial that the cooperation

> between White and Black does not extend to Black ignore White's putting

> his King in check, or indeed put Black's own King in check; and in

> selfmates it is perhaps even more crucial that Black is forced only

> to reach a checkmate position, not to actually capture the King --

> and along the way Black's options are usually restricted by the

> obligation not to move into check or remain in check, even if

> Black would prefer to do so. So unless your SC variant also

> replaces win-by-checkmate by win-by-K-capture, it is still a

> natural question whether in SC proof game one is allowed to

> deliberately allow an solidarity-breaking move en route to the

> desired diagram.

Yes. And, moreover, if one want to construct a SC-legal (or not)
position problem, one have to precisely define which are the SC-legal
moves, as a SC-legal position is obtained from the initial game array
via a series of SC-legal moves.

To define the SC-legal moves, we must in particular define the
SC-checking moves, as the further legal moves are (generally) not the
same if the side on move is in check or not. In the first case, the
range of legal moves is restricted as the side on move must parry the
check (and is checkmated if he can't).


More information about the Retros mailing list