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: Thomas is not a writer. If it is windy, then Mary is driving a car. Mary is not driving a car. Thomas is a writer if and only if Susan is fast.
It is not windy can be inferred via the modus tollens rule. Thomas is not a writer and Mary is not driving a car can be inferred via the conjunction rule. Mary is not driving a car and Thomas is not a writer can be inferred via the conjunction rule. If Thomas were a writer, then Susan is fast can be inferred via the biconditional elimination rule. If Susan were fast, then Thomas is a writer can be inferred via the biconditional elimination rule. Susan is not fast can be inferred via the biconditional elimination rule.