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: Linda is not writing a letter. Robert is taking a plane if and only if Patricia is a lawyer. Robert is not taking a plane. Linda is writing a letter or James is running.
James is running can be inferred via the disjunctive syllogism rule. Linda is not writing a letter and Robert is not taking a plane can be inferred via the conjunction rule. Robert is not taking a plane and Linda is not writing a letter can be inferred via the conjunction rule. If Robert takes a plane, then Patricia is a lawyer can be inferred via the biconditional elimination rule. If Patricia were a lawyer, then Robert is taking a plane can be inferred via the biconditional elimination rule. Patricia is not a lawyer can be inferred via the biconditional elimination rule.