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 not playing squash. John is playing squash if and only if it is overcast. It is overcast or John is not playing squash. If William goes running, then it is overcast.
If John plays squash, then it is overcast can be inferred via the rewriting rule. If John plays squash, then it is overcast can be inferred via the biconditional elimination rule. If it is overcast, then John is playing squash can be inferred via the biconditional elimination rule. It is not overcast can be inferred via the biconditional elimination rule.