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 sunny, then Mary is a musician. Mary is a musician if and only if Joseph is fast. It is not snowing. It is snowing if and only if Joseph is fast.
If Mary were a musician, then Joseph is fast can be inferred via the biconditional elimination rule. If it snows, then Joseph is fast can be inferred via the biconditional elimination rule. If Joseph were fast, then Mary is a musician can be inferred via the biconditional elimination rule. If Joseph were fast, then it is snowing can be inferred via the biconditional elimination rule. Joseph is not fast can be inferred via the biconditional elimination rule.