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: Barbara is a scientist. For all x_5, x_5 is a scientist if and only if x_5 will cook.
There is at least one x for which x is a scientist can be inferred via the existential generalization rule. For all x_5, if x_5 were a scientist, then x_5 is cooking can be inferred via the universal biconditional elimination rule. For all x_5, if x_5 cooks, then x_5 is a scientist can be inferred via the universal biconditional elimination rule.