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 Linda listens to a song, then John is playing squash. If Thomas reads a book, then Linda is listening to a song. If John plays squash, then Linda is listening to a song. If John plays squash, then Thomas is reading a book.
If Linda listens to a song, then Thomas is reading a book can be inferred via the transitivity rule. If Thomas reads a book, then John is playing squash can be inferred via the transitivity rule. If John plays squash, then Linda is listening to a song can be inferred via the transitivity rule. Linda is listening to a song if and only if John is playing squash can be inferred via the biconditional introduction rule. John is playing squash if and only if Linda is listening to a song can be inferred via the biconditional introduction rule.