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: Patricia is a lawyer. It is not overcast. Elisabeth is a poet if and only if it is overcast.
Patricia is a lawyer and it is not overcast can be inferred via the conjunction rule. It is not overcast and Patricia is a lawyer can be inferred via the conjunction rule. If Elisabeth were a poet, then it is overcast can be inferred via the biconditional elimination rule. If it is overcast, then Elisabeth is a poet can be inferred via the biconditional elimination rule. Elisabeth is not a poet can be inferred via the biconditional elimination rule.