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: Mary is not playing squash. It is snowing if and only if Mary is playing squash. For all x_20, x_20 is a mechanic and x_20 will play a game.
If it snows, then Mary is playing squash can be inferred via the biconditional elimination rule. If Mary plays squash, then it is snowing can be inferred via the biconditional elimination rule. It is not snowing can be inferred via the biconditional elimination rule. For all x_20, x_20 is a mechanic can be inferred via the universal simplification rule. For all x_20, x_20 will play a game can be inferred via the universal simplification rule.