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 Barbara were fast, then it is late. If John were a police officer, then Linda is a carpenter. Linda is a carpenter. If John were a police officer, then it is late. If Linda were a carpenter, then John is a police officer.
John is a police officer can be inferred via the modus ponens rule. If Linda were a carpenter, then it is late can be inferred via the transitivity rule. John is a police officer if and only if Linda is a carpenter can be inferred via the biconditional introduction rule. Linda is a carpenter if and only if John is a police officer can be inferred via the biconditional introduction rule.