What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_12, if x_12 listens to a song, then x_12 is climbing a mountain. There is at least one x_12 for which if x_12 climbs a mountain, then x_12 is fast. For all x_12, if x_12 climbs a mountain, then x_12 is listening to a song. For all x_12, if x_12 were fast, then x_12 is climbing a mountain.
For all x_12, if x_12 were fast, then x_12 is listening to a song. There is at least one x_12 for which if x_12 listens to a song, then x_12 is fast. For all x_12, x_12 will listen to a song if and only if x_12 will climb a mountain. For all x_12, x_12 will climb a mountain if and only if x_12 will listen to a song. There is at least one x_12 for which x_12 will climb a mountain if and only if x_12 is fast. There is at least one x_12 for which x_12 is fast if and only if x_12 will climb a mountain.