What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: If Sarah were a soldier, then Mary is a sailor. If Elisabeth takes a plane, then Mary is not a sailor. Mary is a sailor if and only if it is late. It is late or Sarah is a soldier.
If Mary were a sailor, then it is late can be inferred via the biconditional elimination rule. If it is late, then Mary is a sailor can be inferred via the biconditional elimination rule.