∀x ((Mammal(x) ∧ LayEgg(x)) → (Platypus(x) ⊕ Echidna(x)))
∀x (Platypuses(x) → ¬Hyrax(x))
∀x (Echidnas(x) → ¬Hyrax(x))
∀x (Mammal(x) → ¬Invertebrate(x))
∀x (Animal(x) → (Vertebrate(x) ∨ Invertebrate(x)))
∀x (Mammal(x) → Animal(x))
∀x (Hyrax(x) → Mammal(x))
∀x (Grebes(x) → LayEgg(x))
∀x (Grebes(x) → (¬Platypuses(x) ∧ ¬Echidnas(x)))
∃x (Hyrax(x) ∧ LayEgg(x))