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 William plays squash, then it is overcast. William is not playing squash. William is playing squash if and only if it is overcast. If Thomas were a server, then it is overcast.
If William plays squash, then it is overcast can be inferred via the biconditional elimination rule. If it is overcast, then William is playing squash can be inferred via the biconditional elimination rule. It is not overcast can be inferred via the biconditional elimination rule.