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: Richard is poor. Sarah is a scientist. Joseph is writing a letter.
Richard is poor and Sarah is a scientist can be inferred via the conjunction rule. Richard is poor and Joseph is writing a letter can be inferred via the conjunction rule. Sarah is a scientist and Richard is poor can be inferred via the conjunction rule. Sarah is a scientist and Joseph is writing a letter can be inferred via the conjunction rule. Joseph is writing a letter and Richard is poor can be inferred via the conjunction rule. Joseph is writing a letter and Sarah is a scientist can be inferred via the conjunction rule.