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 is overcast, then Susan is listening to a song. If Susan listens to a song, then David is working. If David works, then it is overcast. If David works, then Susan is listening to a song.
If it is overcast, then David is working can be inferred via the transitivity rule. If Susan listens to a song, then it is overcast can be inferred via the transitivity rule. If David works, then Susan is listening to a song can be inferred via the transitivity rule. Susan is listening to a song if and only if David is working can be inferred via the biconditional introduction rule. David is working if and only if Susan is listening to a song can be inferred via the biconditional introduction rule.