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_6, if x_6 plays squash, then x_6 is reading a book. For all x_6, if x_6 reads a book, then x_6 is drinking water. For all x_6, x_6 will play squash if and only if x_6 will drink water.
For all x_6, if x_6 plays squash, then x_6 is drinking water can be inferred via the universal transitivity rule. For all x_6, if x_6 plays squash, then x_6 is drinking water can be inferred via the universal biconditional elimination rule. For all x_6, if x_6 drinks water, then x_6 is playing squash can be inferred via the universal biconditional elimination rule.