Originally Posted by

**bmp05** Hello everyone,

I'm having problems with the following type of tutorial questions (yes, there are more of them):

Use logic notation to express the following:

"There is at most one x with P(x)"

I understand that to mean, "if there exists an x such that P(x), then for all other x not P(x)."

$\displaystyle

(\exists x)[P(x)] \rightarrow (\forall y)[\neg P(x)], x \neq y

$

but this is wrong, or at least badly expressed. Would the following be right?

$\displaystyle

(\exists x, \forall y; x \neq y)[P(x)]

$