Posted by Ben C on 03/30/07 09:43

On 2007-03-30, Chris F.A. Johnson <cfajohnson@gmail.com> wrote:
> On 2007-03-29, Ben C wrote:
>> On 2007-03-29, dorayme <doraymeRidThis@optusnet.com.au> wrote:
>> [...]
>>>> >If you want a chess puzzle (and the graphic is not so bad), look
>>>> >at:
>>>> >
>>>> ><http://members.optushome.com.au/droovies/binHassad/missingKing.ht
>>>> >ml>
>
> That is taken (uncredited) from "Chess Mysteries of the Arabian
> Knights" by Raymond Smullyan.
>
>> I give up.
>>
>> I figure the white king must have been on either b3 or c2 since as
>> things stand the black king is in check. The white bishop attacking it
>> can only have got where it is along that same diagonal, and the black
>> king can't have moved into check. So something must have moved off that
>> diagonal opening the attack.
>>
>> The white king couldn't have been on c2, since there is no way two kings
>> can end up on adjacent squares-- to move a king next to another king is
>> to move it into check, which is illegal.
>>
>> That leaves b3, from where it moved to either a3 or c3 out of check
>> itself and checking black. But it is not possible for it to have got
>> into the situation on b3 attacked by both the rook and bishop in the
>> first place, since they can't both have got there in a single move.
>
> What could the last three moves (White, Black, and White) have been?

Thanks for the hint. I had another look at it, gave up again, and then
checked my email where dorayme had explained it. Very clever. I won't
spoil it for anyone else by posting the solution.

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