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: Jessica is not a nurse. If it is late, then James is writing a letter. James is not writing a letter. If it is sunny, then Jessica is a nurse.
It is not late can be inferred via the modus tollens rule. It is not sunny can be inferred via the modus tollens rule. Jessica is not a nurse and James is not writing a letter can be inferred via the conjunction rule. James is not writing a letter and Jessica is not a nurse can be inferred via the conjunction rule.