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: There is at least one x_8 for which if x_8 listens to a song, then x_8 is climbing a mountain. For all x_8, x_8 is a taxi driver if and only if x_8 is a writer. For all x_8, x_8 will listen to a song or x_8 is a writer. For all x_8, if x_8 were a taxi driver, then x_8 is climbing a mountain.
For all x_8, if x_8 were a taxi driver, then x_8 is a writer can be inferred via the universal biconditional elimination rule. For all x_8, if x_8 were a writer, then x_8 is a taxi driver can be inferred via the universal biconditional elimination rule.