∃x (Teacher(x) ∧ WorkAt(x, pool) ∧ ¬Nice(x))
∀x (Teacher(x) ∧ WorkAt(x, pool) → PoolManager(x))
∀x (PoolManager(x) → Lifeguard(x))
∀x (Lifeguard(x) → WorkAt(x, pool))
¬WorkAt(mary, pool)
Nice(mary) ∧ Teacher(mary) ∧ WorkAt(mary, pool)