R1: Every monotreme is a mammal. R2: Everything that has some fur is a mammal. R3: Nothing that lays some eggs is a mammal. R4: Nothing that has a bill is a mammal. R1 overrides R3. R2 overrides R4. Every platypus is a monotreme. Every platypus has some fur. Every platypus lays some eggs. Every platypus has a bill. John is a platypus.