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_13 for which x_13 is a server or x_13 will play a game. For all x_13, x_13 is a mechanic if and only if x_13 is a server. For all x_13, if x_13 plays a game, then x_13 is a mechanic. For all x_13, x_13 is a musician.
For all x_13, if x_13 were a mechanic, then x_13 is a server can be inferred via the universal biconditional elimination rule. For all x_13, if x_13 were a server, then x_13 is a mechanic can be inferred via the universal biconditional elimination rule.