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: Elisabeth is not playing tennis. If Elisabeth plays tennis, then it is late. If it is late, then Elisabeth is playing tennis. Elisabeth is running.
It is not late can be inferred via the modus tollens rule. Elisabeth is not playing tennis and Elisabeth is running can be inferred via the conjunction rule. Elisabeth is running and Elisabeth is not playing tennis can be inferred via the conjunction rule. Elisabeth is playing tennis if and only if it is late can be inferred via the biconditional introduction rule. It is late if and only if Elisabeth is playing tennis can be inferred via the biconditional introduction rule.