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_2, x_2 will not go running. There is at least one x_2 for which if x_2 writes a letter, then x_2 is sad. For all x_2, x_2 will go running or x_2 will write a letter.
For all x_2, x_2 will write a letter can be inferred via the universal disjunctive syllogism rule.