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: If Jessica were not happy, then John is sleeping. It is not windy. It is windy if and only if Charles is climbing a mountain. If Jessica were happy, then Charles is climbing a mountain.
If it is windy, then Charles is climbing a mountain can be inferred via the biconditional elimination rule. If Charles climbs a mountain, then it is windy can be inferred via the biconditional elimination rule. Charles is not climbing a mountain can be inferred via the biconditional elimination rule.