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: Elisabeth is playing tennis. William is fast if and only if Mary is listening to a song. It is cloudy or Mary is listening to a song. If it is cloudy, then William is fast.
If William were fast, then Mary is listening to a song can be inferred via the biconditional elimination rule. If Mary listens to a song, then William is fast can be inferred via the biconditional elimination rule.