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: William is not an artist. If William were an artist, then it is late. If it is not late, then it is cold. If it is late, then William is an artist.
It is not late can be inferred via the modus tollens rule. William is an artist if and only if it is late can be inferred via the biconditional introduction rule. It is late if and only if William is an artist can be inferred via the biconditional introduction rule.