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 late if and only if John is playing squash. John is not playing squash. If John plays squash, then it is late.
If it is late, then John is playing squash can be inferred via the biconditional elimination rule. If John plays squash, then it is late can be inferred via the biconditional elimination rule. It is not late can be inferred via the biconditional elimination rule.