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: It is late if and only if Jennifer is a sailor. It is late if and only if Robert is sad.
If it is late, then Jennifer is a sailor can be inferred via the biconditional elimination rule. If it is late, then Robert is sad can be inferred via the biconditional elimination rule. If Jennifer were a sailor, then it is late can be inferred via the biconditional elimination rule. If Robert were sad, then it is late can be inferred via the biconditional elimination rule.