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: Barbara is sleeping if and only if Elisabeth is a scientist. If Richard listens to a song, then Barbara is sleeping. Elisabeth is not a scientist. It is sunny.
Elisabeth is not a scientist and it is sunny can be inferred via the conjunction rule. It is sunny and Elisabeth is not a scientist can be inferred via the conjunction rule. If Barbara sleeps, then Elisabeth is a scientist can be inferred via the biconditional elimination rule. If Elisabeth were a scientist, then Barbara is sleeping can be inferred via the biconditional elimination rule. Barbara is not sleeping can be inferred via the biconditional elimination rule.