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 late, then Richard is taking a plane. It is late if and only if Sarah is curious. Sarah is curious if and only if Richard is taking a plane.
If it is late, then Sarah is curious can be inferred via the biconditional elimination rule. If Sarah were curious, then Richard is taking a plane can be inferred via the biconditional elimination rule. If Sarah were curious, then it is late can be inferred via the biconditional elimination rule. If Richard takes a plane, then Sarah is curious can be inferred via the biconditional elimination rule.