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: Robert is not a sailor. Robert is a sailor or Richard is a nurse. Richard is making tea. If Susan plays squash, then Richard is not making tea.
Susan is not playing squash can be inferred via the modus tollens rule. Richard is a nurse can be inferred via the disjunctive syllogism rule. Robert is not a sailor and Richard is making tea can be inferred via the conjunction rule. Richard is making tea and Robert is not a sailor can be inferred via the conjunction rule.