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 Robert plays squash, then Linda is not a politician. Sarah is a carpenter if and only if Robert is playing squash. Linda is a politician.
Robert is not playing squash can be inferred via the modus tollens rule. If Sarah were a carpenter, then Robert is playing squash can be inferred via the biconditional elimination rule. If Robert plays squash, then Sarah is a carpenter can be inferred via the biconditional elimination rule.