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_1, x_1 is an electrician or x_1 is a lawyer. There is at least one x_1 for which if x_1 were an electrician, then x_1 is climbing a mountain. For all x_1, x_1 will not climb a mountain.
There is at least one x_1 for which x_1 is not an electrician can be inferred via the existential modus tollens rule.