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: It is overcast if and only if Elisabeth is playing tennis. It is late or it is not overcast. John is a nurse if and only if it is late. John is not a nurse.
If it is overcast, then it is late can be inferred via the rewriting rule. If it is overcast, then Elisabeth is playing tennis can be inferred via the biconditional elimination rule. If John were a nurse, then it is late can be inferred via the biconditional elimination rule. If Elisabeth plays tennis, then it is overcast can be inferred via the biconditional elimination rule. If it is late, then John is a nurse can be inferred via the biconditional elimination rule. It is not late can be inferred via the biconditional elimination rule.