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_7, if x_7 drinks water, then x_7 is a poet. For all x_7, if x_7 were a poet, then x_7 is a soldier. There is at least one x_7 for which if x_7 were a poet, then x_7 is drinking water.
For all x_7, if x_7 drinks water, then x_7 is a soldier can be inferred via the universal transitivity rule. There is at least one x_7 for which x_7 is a poet if and only if x_7 will drink water can be inferred via the existential biconditional introduction rule. There is at least one x_7 for which x_7 will drink water if and only if x_7 is a poet can be inferred via the existential biconditional introduction rule.