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_12, x_12 is a writer or x_12 will not drink water. There is at least one x_12 for which if x_12 were a sailor, then x_12 is drinking water. For all x_12, x_12 is a sailor if and only if x_12 is a writer.
For all x_12, if x_12 drinks water, then x_12 is a writer can be inferred via the universal rewriting rule. For all x_12, if x_12 were a sailor, then x_12 is a writer can be inferred via the universal biconditional elimination rule. For all x_12, if x_12 were a writer, then x_12 is a sailor can be inferred via the universal biconditional elimination rule.