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: For all x_21, x_21 is a musician and x_21 is a cashier. If Linda writes a letter, then it is overcast. Linda is writing a letter.
It is overcast can be inferred via the modus ponens rule. For all x_21, x_21 is a musician can be inferred via the universal simplification rule. For all x_21, x_21 is a cashier can be inferred via the universal simplification rule.