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: John is running if and only if Elisabeth is a writer. It is not overcast. If it is overcast, then Elisabeth is a writer. If Elisabeth were a writer, then it is overcast.
Elisabeth is not a writer can be inferred via the modus tollens rule. It is overcast if and only if Elisabeth is a writer can be inferred via the biconditional introduction rule. Elisabeth is a writer if and only if it is overcast can be inferred via the biconditional introduction rule. If John goes running, then Elisabeth is a writer can be inferred via the biconditional elimination rule. If Elisabeth were a writer, then John is running can be inferred via the biconditional elimination rule.