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 it is cold, then Robert is a mechanic. If Robert were a mechanic, then it is late. If it is late, then it is cold. If it is late, then Robert is a mechanic.
If it is cold, then it is late can be inferred via the transitivity rule. If Robert were a mechanic, then it is cold can be inferred via the transitivity rule. If it is late, then Robert is a mechanic can be inferred via the transitivity rule. Robert is a mechanic if and only if it is late can be inferred via the biconditional introduction rule. It is late if and only if Robert is a mechanic can be inferred via the biconditional introduction rule.