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: For all x_2, x_2 will listen to a song if and only if x_2 will write a letter. There is at least one x_2 for which x_2 will listen to a song or x_2 is not a police officer.
There is at least one x_2 for which if x_2 were a police officer, then x_2 is listening to a song can be inferred via the existential rewriting rule. For all x_2, if x_2 listens to a song, then x_2 is writing a letter can be inferred via the universal biconditional elimination rule. For all x_2, if x_2 writes a letter, then x_2 is listening to a song can be inferred via the universal biconditional elimination rule.