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 Thomas plays squash, then Karen is listening to a song. Thomas is playing squash if and only if Karen is reading a book. Karen is not reading a book. If Karen listens to a song, then Thomas is playing squash.
Thomas is playing squash if and only if Karen is listening to a song can be inferred via the biconditional introduction rule. Karen is listening to a song if and only if Thomas is playing squash can be inferred via the biconditional introduction rule. If Thomas plays squash, then Karen is reading a book can be inferred via the biconditional elimination rule. If Karen reads a book, then Thomas is playing squash can be inferred via the biconditional elimination rule. Thomas is not playing squash can be inferred via the biconditional elimination rule.