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_7, x_7 is a server or x_7 will climb a mountain. For all x_7, x_7 is a sailor if and only if x_7 will climb a mountain. There is at least one x_7 for which x_7 is not a server or x_7 will play a game. For all x_7, if x_7 plays a game, then x_7 is a sailor.
There is at least one x_7 for which x_7 will climb a mountain or x_7 will play a game can be inferred via the existential resolution rule. For all x_7, if x_7 were a sailor, then x_7 is climbing a mountain can be inferred via the universal biconditional elimination rule. For all x_7, if x_7 climbs a mountain, then x_7 is a sailor can be inferred via the universal biconditional elimination rule.