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 if and only if x_12 will play squash. Sarah is bored if and only if Sarah is playing squash. Sarah is bored or Sarah is a writer.
If Sarah drinks water, then Sarah is bored can be inferred via the rewriting rule. If Sarah were bored, then Sarah is playing squash can be inferred via the biconditional elimination rule. If Sarah plays squash, then Sarah is bored can be inferred via the biconditional elimination rule. For all x_12, if x_12 were a writer, then x_12 is playing squash can be inferred via the universal biconditional elimination rule. For all x_12, if x_12 plays squash, then x_12 is a writer can be inferred via the universal biconditional elimination rule.