What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? William is a poet if and only if Linda is a writer. If Linda were a writer, then Susan is cooking. William is not a poet. If Susan cooks, then Thomas is listening to a song. If Thomas listens to a song, then Linda is a writer.
If Linda were a writer, then Thomas is listening to a song. If Susan cooks, then Linda is a writer. If Thomas listens to a song, then Susan is cooking. If William were a poet, then Linda is a writer. If Linda were a writer, then William is a poet. Linda is not a writer.