The domain of x, y is the set of all natural numbers. Natural numbers are counting numbers: 1,2,3,.... Consider the following predicates.
P(x):x is an odd number
Q(x,y):2x
O ⌐ ∃x(P(x) ∧ Q(5,x))
O ∀x(P(x) ↔ ⌐ Q(x,y))
O ∀y∀x(P(y) → Q(x,y))
O P(4) ∨ ⌐Q(x,5)
O p(11) ∧ Q(3,5)