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 sunny or it is not overcast. If it is sunny, then Susan is an artist. Karen is a police officer if and only if it is overcast. Susan is not an artist.
It is not sunny can be inferred via the modus tollens rule. If it is overcast, then it is sunny can be inferred via the rewriting rule. If Karen were a police officer, then it is overcast can be inferred via the biconditional elimination rule. If it is overcast, then Karen is a police officer can be inferred via the biconditional elimination rule.