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1.  BigDoggProblem
08 Jun '14 19:59 / 1 edit
What is this site coming to when a guy can't even keep control of a hijacked thread.

Challenge: construct a legal position where A)White is attacking NONE of black's 16 pieces; but after he moves, he is B) attacking ALL of Black's 16 pieces.

"Attack" means "threaten to legally capture".

Good luck!
2.  DeepThought
08 Jun '14 22:47
Originally posted by BigDoggProblem
What is this site coming to when a guy can't even keep control of a hijacked thread.

Challenge: construct a legal position where [b]A)
White is attacking NONE of black's 16 pieces; but after he moves, he is B) attacking ALL of Black's 16 pieces.

"Attack" means "threaten to legally capture".

Good luck![/b]

After Kg1 or Ke1 every black piece is threatened. The position is legal if implausible.
3.  BigDoggProblem
09 Jun '14 02:24
Originally posted by DeepThought
[fen]3bQ3/4pppp/p1n2k1B/1p1r2N1/PNppP1n1/1PPq3b/r3BKPP/R2Q1R2 w KQkq - 0 1[/fen]
After Kg1 or Ke1 every black piece is threatened. The position is legal if implausible.
Ahh yes, I did leave this possibility open.

So I must add C) white is not in check.
4. 09 Jun '14 09:40
I can get as high as ten attack Black pieces after White's move. I'll be surprised if this can be improved upon.
5.  DeepThought
09 Jun '14 13:02 / 1 edit
Originally posted by BigDoggProblem
Ahh yes, I did leave this possibility open.

white is not in check.[/b]

Rf1+ should do it then.
6. 09 Jun '14 13:11 / 1 edit
Unfortunately this doesn't quite comply with part A - "White is attacking NONE of black's 16 pieces". In fact 15 of Black's 16 pieces are under attack in the initial position!
7. 09 Jun '14 13:21 / 3 edits
I thought of another solution over lunch.

If White is one of four people playing that well known chess variant, 3d exchange chess (aka 3d bughouse), with the agreed rule that pieces can be put on with check, then in the following position:

Top board:

Middle board:

Bottom board:

He can play his queen to e4 in the middle board, simultaneously attacking all 16 of Black's pieces.
8. 09 Jun '14 14:13
Last attempt. None of Black's pieces at start, all of them attacked after White's second move.
9.  BigDoggProblem
09 Jun '14 15:16
It can be done in orthodox chess in a single move.

Hint:
use pins
10. 09 Jun '14 15:50
Thanks for the hint. I'm not happy with the white pawn on f6, but I can't get rid of it (stops white rook attacking f4):
11.  BigDoggProblem
09 Jun '14 16:07 / 1 edit
Originally posted by Data Fly
Thanks for the hint. I'm not happy with the white pawn on f6, but I can't get rid of it (stops white rook attacking f4):
[pgn][/pgn]
Almost! The only problem is Pf6 works a bit too well; bPf4 is still not attacked after 1.Nc6.
12. 09 Jun '14 16:14
Let's go for Nd5 instead then.
13.  DeepThought
09 Jun '14 16:18
Originally posted by Data Fly
Unfortunately this doesn't quite comply with part A - "White is attacking NONE of black's 16 pieces". In fact 15 of Black's 16 pieces are under attack in the initial position!
Forgot about that, it was a fairly natural thing to wish to modify my original position rather than start from scratch. The problem is I'd have to.
14.  BigDoggProblem
09 Jun '14 16:22
Originally posted by Data Fly
Let's go for Nd5 instead then.
[pgn]
[FEN "5B2/1b2N1R1/1r1p1qP1/4p1p1/1r1p1p1p/2n1kN2/3p3p/4n1bK w - - 0 1"]
[SetUp "1"]
{
--------------
. k . q . B . .
r b . . N R . .
. . . p . P . .
n . . . p . p .
. r . p . p . p
. . . . . N . .
. . . p . . . p
. . . . n . b K
white to play
--------------
}
1. Nd5+
[/pgn]
Very good. That matrix is so good that I can get rid of two white units.

15. 09 Jun '14 16:25 / 1 edit
Originally posted by BigDoggProblem
[b]Very good. That matrix is so good that I can get rid of two white units.
Unfortunately this doesn't quite comply with part A - "White is attacking NONE of black's 16 pieces".

However move Black's b7 bishop along to a7 and plonk a White rook onto h7 and you've got rid of the horrible pawn I had to add.