Any Chess Playing Software That Will Not Allow This Type Of Position?

[Pargat Perrer]

The following chess FEN position...

q1r1k1rQ/7p/Pppp4/1pn1p1NP/1BbpP2P/3PP1p1/3K2PR/1b1n1B2 w - - 0 50

is illegal. Black has all 8 Pawns, yet Black also has both Bishops being on the same color square. This is impossible in chess. Only a Pawn promotion can give you 2 Bishops on the same color square.

Is there any chess playing software that will NOT allow the setup of this type of position, where one side or the other has all 8 Pawns but also has both Bishops on the same color square? Does Chessbase allow one to setup this kind of position? I don't have Chessbase so I don't know. I do have SCID and it allows this position.

NOTE: this position came up in a game of Hostage Chess, invented by Dr. John Leslie of Victoria, B.C.

In Hostage Chess, this type of position is legal because a Bishop could be captured, and then later brought back onto the board but on the same color square as the other Bishop for that side, even if all 8 Pawns are still on the board for that side.

EDIT: I have verified that SCID will report an error if you try and give either side an extra minor piece or Queen when that side has all 8 Pawns still on the board.

So the problem seems to be limited to the two-Bishops-on-the-same-color-square situation.

[Egidijus Zeromskis]

The following chess FEN position...

q1r1k1rQ/7p/Pppp4/1pn1p1NP/1BbpP2P/3PP1p1/3K2PR/1b1n1B2 w - - 0 50

is illegal. Black has all 8 Pawns, yet Black also has both Bishops being on the same color square. This is impossible in chess. Only a Pawn promotion can give you 2 Bishops on the same color square.

Is there any chess playing software that will NOT allow the setup of this type of position, where one side or the other has all 8 Pawns but also has both Bishops on the same color square? Does Chessbase allow one to setup this kind of position? I don't have Chessbase so I don't know. I do have SCID and it allows this position.

It's illegal to get that position in the normal game, however no one is forbidding you to setup on the board as the initial starting point.

I think Chessbase would give a message that the position is illegal and then ask if to proceed anyway as a training material. Need to look what exactly it says. Though does not mean it would alert on this one.

[Emil Smilovici]

Chessbase (a very old version) won't let me press OK at the end of the position setup.
If I remove one of the black pawns it will allow it.
Of course, moving one Bishop to a black square (e.g. from b1 to a1) will also permit the setup.

[John Upper]

If I remove one of the black pawns it will allow it.
Of course, moving one Bishop to a black square (e.g. from b1 to a1) will also permit the setup.

Ditto for Chessbase 17, which is the current version. It won't even allow the FEN to be posted because "there is no legal position in clipboard", but removing a black pawn allows the position to load.

[Pargat Perrer]

Ditto for Chessbase 17, which is the current version. It won't even allow the FEN to be posted because "there is no legal position in clipboard", but removing a black pawn allows the position to load.

Thank you John and Emil for these reports. Good to know at least Chessbase is on top of this, even going back to older versions.

[Egidijus Zeromskis]

Ditto for Chessbase 17, which is the current version. It won't even allow the FEN to be posted because "there is no legal position in clipboard", but removing a black pawn allows the position to load.

If you really wanna get the position on the CB17:
instead of pasting directly, create new Board, then Position Setup (S), and paste here FEN.
After OK, you'll get the message "The position is illegal, proceed anyway?" Yes.



However, it will not let to start Engine.