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: David is not running. Joseph is climbing a mountain or it is not late. Joseph is climbing a mountain if and only if David is running.
If it is late, then Joseph is climbing a mountain can be inferred via the rewriting rule. If Joseph climbs a mountain, then David is running can be inferred via the biconditional elimination rule. If David goes running, then Joseph is climbing a mountain can be inferred via the biconditional elimination rule. Joseph is not climbing a mountain can be inferred via the biconditional elimination rule.