What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If William were an office clerk, then Elisabeth is sleeping. Elisabeth is not sleeping. Barbara is fast if and only if Linda is listening to a song. Linda is listening to a song if and only if William is an office clerk.
William is not an office clerk. If Barbara were fast, then Linda is listening to a song. If Linda listens to a song, then William is an office clerk. If Linda listens to a song, then Barbara is fast. If William were an office clerk, then Linda is listening to a song.