Hello,

the problem is to show that P isn't logical consequence of Q:

$\displaystyle P = ( \forall x) ( \exists y)r(x,y) $

$\displaystyle Q = ( \exists y) ( \forall x)r(x,y) $

$\displaystyle r$ stands for relation.

Maybe some kind of proof by contradiction would work, but I couldn't make one.

Any help is appreciated. Thanks in advance!