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_15, x_15 is a sailor or x_15 is a police officer. For all x_15, x_15 will climb a mountain if and only if x_15 is a police officer. There is at least one x_15 for which x_15 is not a sailor or x_15 is fast. For all x_15, if x_15 were a server, then x_15 is not fast. For all x_15, x_15 will not climb a mountain.
There is at least one x_15 for which x_15 is a police officer or x_15 is fast can be inferred via the existential resolution rule. For all x_15, if x_15 climbs a mountain, then x_15 is a police officer can be inferred via the universal biconditional elimination rule. For all x_15, if x_15 were a police officer, then x_15 is climbing a mountain can be inferred via the universal biconditional elimination rule. For all x_15, x_15 is not a police officer can be inferred via the universal biconditional elimination rule.