What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_4, if x_4 were a musician, then x_4 is a mechanic. For all x_4, if x_4 were sad, then x_4 is a musician. For all x_4, if x_4 were a mechanic, then x_4 is sad.
For all x_4, if x_4 were a musician, then x_4 is sad. For all x_4, if x_4 were sad, then x_4 is a mechanic. For all x_4, if x_4 were a mechanic, then x_4 is a musician.