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 will take a plane and x_13 will play squash. For all x_13, if x_13 were a cashier, then x_13 is listening to a song. For all x_13, if x_13 takes a plane, then x_13 is working. For all x_13, if x_13 listens to a song, then x_13 is working.
For all x_13, if x_13 were a cashier, then x_13 is working can be inferred via the universal transitivity rule. There is at least one x_13 for which x_13 will take a plane can be inferred via the existential simplification rule. There is at least one x_13 for which x_13 will play squash can be inferred via the existential simplification rule.