Re: Dominoes on a chessboard

"Chip Eastham" <hardmath@[EMAIL PROTECTED]
> a écrit dans le message de news: 
cdd311bd-ec34-4827-84da-41b4358273ee@[EMAIL PROTECTED]
 we can get both the removed and the
remaining (uniquely tilable) ****tions of the
board to be simply connected.  I'll leave this
as a challenge for now.

Still no idea how to prove that N removed squares
are necessary to provoke the unique tiling...

Chip,

[I don't know why the lines of your last post aren't prefixed with '>'.]

I found the following method of doing this. The diagrams show it better
than 
any written explanation I could give.

Even N:

--++++
+--+++
++--++
++++++
++++++
++++++

--++++++
+--+++++
++--++++
+++--+++
++++++++
++++++++
++++++++
++++++++

Odd N:

--+++
+--++
++-++
+++++
+++++

--+++++
+--++++
++--+++
+++-+++
+++++++
+++++++
+++++++

--
Regards,
Colin