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 Michael sleeps, then Susan is not sad. Susan is sad if and only if it is cold. It is cold or Charles is running. If Charles goes running, then Susan is sad.
If Susan were sad, then it is cold can be inferred via the biconditional elimination rule. If it is cold, then Susan is sad can be inferred via the biconditional elimination rule.