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 y, y is a bartender if and only if y will write a letter. For all y, y is a soldier or y is not a bartender. For all y, if y writes a letter, then y is a bartender.
For all y, if y were a bartender, then y is a soldier can be inferred via the universal rewriting rule. For all y, if y were a bartender, then y is writing a letter can be inferred via the universal biconditional elimination rule. For all y, if y writes a letter, then y is a bartender can be inferred via the universal biconditional elimination rule.