I am given
universe of discourse: Z
predicate symbols: q
interpretation: $q(x,y) \iff x + y = 5$
There are two questions two questions which I don't understand:
i) $∀x.∃y.q(x,y)$ is true, I found it to be false
ii) $∀y.∃x.q(x,y)$ is true, I found it to be false
An explanation would be appreciated, thanks.
$∀x.∃y.q(x,y)$ is true because for any x you can choose y to be $(5-x)$ and $q(x,y)$ will be true. Same for the second question.