What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? There is at least one x_9 for which x_9 is a carpenter if and only if x_9 will write a letter. For all x_9, x_9 will climb a mountain if and only if x_9 is a carpenter. For all x_9, x_9 will climb a mountain or x_9 will write a letter.
For all x_9, if x_9 climbs a mountain, then x_9 is a carpenter. There is at least one x_9 for which if x_9 were a carpenter, then x_9 is writing a letter. For all x_9, if x_9 were a carpenter, then x_9 is climbing a mountain. There is at least one x_9 for which if x_9 writes a letter, then x_9 is a carpenter.