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        riddles >> easy >> Chess Position
        
(Message started by: ThudanBlunder on Jun 15^th, 2007, 8:33pm)

Title: Chess Position
Post by ThudanBlunder on Jun 15^th, 2007, 8:33pm

What can be said about this position?

Title: Re: Chess Position
Post by rmsgrey on Jun 16^th, 2007, 7:09am

on 06/15/07 at 20:33:30, ThudanBlunder wrote:

What can be said about this position?

[hide]The board's upside down[/hide]?

edit: On second thoughts:

[hide]Someone's cheated[/hide]

edit2: On third thoughts:

[hide]probably still someone's cheated, but it'll take more work to prove it[/hide]

edit3: Fourth and final thoughts:

[hide]OK, not that much more work - It's Black's move and no-one's cheated yet.[/hide]

edit4: Fifth and really final thoughts:

[hide]OK, there's no possible last move for white, so someone has cheated after all.[/hide]

Title: Re: Chess Position
Post by Grimbal on Jun 16^th, 2007, 8:23am

[hide] I don't see why someone must have cheated. It's white's turn, that's all. [/hide]
Besides, I would say the players are not seriously trying to win.

Title: Re: Chess Position
Post by ThudanBlunder on Jun 16^th, 2007, 10:03am

on 06/16/07 at 08:23:19, Grimbal wrote:

[hide] I don't see why someone must have cheated. It's white's turn, that's all. [/hide]

Perhaps a recount is required. ;)

on 06/16/07 at 07:09:16, rmsgrey wrote:

[hide]OK, there's no possible last move for white, so someone has cheated after all.[/hide]

Correct, [hide]though I would just say that the position is impossible.[/hide]

Title: Re: Chess Position
Post by Grimbal on Jun 18^th, 2007, 1:14am

on 06/16/07 at 07:09:16, rmsgrey wrote:

[hide]OK, not that much more work - It's Black's move and no-one's cheated yet.[/hide]

edit4: Fifth and really final thoughts:

[hide]OK, there's no possible last move for white, so someone has cheated after all.[/hide]

I follow you up to: [hide]It's Black's move and no-one's cheated yet.[/hide]
Which is is compatible with: [hide]OK, there's no possible last move for white, ...[/hide]

But I don't see how you can conclude: [hide]..., so someone has cheated after all.[/hide]

???

Title: Re: Chess Position
Post by rmsgrey on Jun 18^th, 2007, 7:46am

on 06/18/07 at 01:14:43, Grimbal wrote:

OK, the final conclusion is a little bit of a stretch. I should have said: [hide]..., so the position was not arrived at by playing chess according to the rules[/hide]

The key observations in my thought process:

1) [hide]Every legal move so far must have moved a piece between two squares of different colours, creating a measurable parity. Since black and white have different parities, it must be black's move.[/hide]
2) [hide]The only square which a white piece could otherwise have come from which is unoccupied is f6, and the knight would have had the black king in check there, so there's no position from which white could have moved to reach the position shown[/hide]

Title: Re: Chess Position
Post by Grimbal on Jun 18^th, 2007, 8:30am

Aaah, OK. The [hide]parity argument[/hide] is what I didn't get. Thanks.