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 John climbs a mountain, then Thomas is working. If it snows, then John is climbing a mountain. If Thomas works, then John is climbing a mountain.
If it snows, then Thomas is working can be inferred via the transitivity rule. John is climbing a mountain if and only if Thomas is working can be inferred via the biconditional introduction rule. Thomas is working if and only if John is climbing a mountain can be inferred via the biconditional introduction rule.