Legal?

Is the position legal?

Originally posted by BigDoggProblem
[fen]8/5N2/2kP1r2/7b/P7/6KB/7r/2R3BQ[/fen]
Is the position legal?

of course its not, why would you ask if it was?
can't have double check with the queen and rook, also, if the queen was to check, it can't have moved, which means that the rook was blocking it, meaning that BLACK moved his rook out of the way, leaving the queen checking, an illegal move.

Originally posted by abejnood
of course its not, why would you ask if it was?
can't have double check with the queen and rook, also, if the queen was to check, it can't have moved, which means that the rook was blocking it, meaning that BLACK moved his rook out of the way, leaving the queen checking, an illegal move.

Why is there a pawn on a4?

Originally posted by BigDoggProblem
[fen]8/5N2/2kP1r2/7b/P7/6KB/7r/2R3BQ[/fen]
Is the position legal?

Oh yes it is.



.......Rf6+
Kg3. d5
c5d6xd5 (en passant) and we are there.

skeeter

Nope. Forgot about the bishop check, but anyway, it's white's en passant capture that permits the rook / queen double check.

skeeter

Originally posted by BigDoggProblem
Why is there a pawn on a4?

And why is there a knight at f7?

Originally posted by ilywrin
And why is there a knight at f7?

Pawn on a4 and knight f7 are helpful for a checkmate.

Originally posted by jfkjmh
Pawn on a4 and knight f7 are helpful for a checkmate.

What?? The question is "can the displayed position be reached legally" - not, who can be mated. Jesus wept.

skeeter

Okay, then the position is perfectly legal (only you have to assume two en passants happened)
Let's see if I can get the Fen right from the first try:


So the last moves were 1.g4 fxg++ 2.Kxg3+ d5 3.cxd#
EDIT: sorry didn't get the fen right from the first time 🙁

Originally posted by ilywrin
Okay, then the position is perfectly legal (only you have to assume two en passants happened)
Let's see if I can get the Fen right from the first try:
[fen]8/3p1N2/2k2r2/2P4b/P4p2/5K1B/6Pr/2R3BQ w - - 0 1 [/fen]

So the last moves wer ...[text shortened]... cxd#
EDIT: sorry didn't get the fen right from the first time 🙁

That's right, ilywrin. Two ep captures must have occurred for the position to be legal. The problem was composed by Pal Benko and appeared in StrateGems in 1999.

Pa4 and Nf7 appear to be only needed for the finale to be mate. (An 'artistic touch' from the author, but not relevant to the solution). I'd prefer the problem with less material on the board instead.


Same solution.

Originally posted by BigDoggProblem
That's right, ilywrin. Two ep captures must have occurred for the position to be legal. The problem was composed by Pal Benko and appeared in StrateGems in 1999.

Pa4 and Nf7 appear to be only needed for the finale to be mate. (An 'artistic touch' from the author, but not relevant to the solution). I'd prefer the problem with less material on the board instead.

[fen]8/8/2kP1r2/7b/8/6KP/7r/2R4B[/fen]
Same solution.

This is illegal however since the bishop at h1 cannot get there if there is/was a white pawn at g2.

Originally posted by ilywrin
This is illegal however since the bishop at h1 cannot get there if there is/was a white pawn at g2.

D'oh! Unfortunately, this means I'm stuck with something like...


I have to use Ng2 because after -1.axb6ep+ b7-b5 -2.Kd3xPe3+ dxe3ep+ -3.e2-e4, a Pg2 would make the position illegal again (Rf2 no exit!).

Originally posted by BigDoggProblem
D'oh! Unfortunately, this means I'm stuck with something like...
[fen]8/8/kP1r4/5b2/8/4KP2/5rN1/R4B2 b - - 0 3[/fen]

I have to use Ng2 because after -1.axb6ep+ b7-b5 -2.Kd3xPe3+ dxe3ep+ -3.e2-e4, a Pg2 would make the position illegal again (Rf2 no exit!).

And you need a White piece at g2, why exactly?
EDIT: Nevermind just saw it 😉