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 Charles were an artist, then it is not cold. It is cold. For all x_12, x_12 is fast if and only if x_12 is an artist.
Charles is not an artist can be inferred via the modus tollens rule. For all x_12, if x_12 were fast, then x_12 is an artist can be inferred via the universal biconditional elimination rule. For all x_12, if x_12 were an artist, then x_12 is fast can be inferred via the universal biconditional elimination rule.