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: If it snows, then Mary is playing tennis. It is snowing if and only if it is overcast. If Mary plays tennis, then it is sunny. If it is sunny, then it is overcast.
If it snows, then it is sunny can be inferred via the transitivity rule. If Mary plays tennis, then it is overcast can be inferred via the transitivity rule. If it snows, then it is overcast can be inferred via the biconditional elimination rule. If it is overcast, then it is snowing can be inferred via the biconditional elimination rule.