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_11, x_11 will play squash or x_11 is a taxi driver. For all x_11, x_11 will drink water if and only if x_11 is a taxi driver. There is at least one x_11 for which x_11 will not play squash or x_11 is a politician. For all x_11, x_11 will drink water or x_11 is not a politician.
There is at least one x_11 for which x_11 is a taxi driver or x_11 is a politician can be inferred via the existential resolution rule. For all x_11, if x_11 were a politician, then x_11 is drinking water can be inferred via the universal rewriting rule. For all x_11, if x_11 drinks water, then x_11 is a taxi driver can be inferred via the universal biconditional elimination rule. For all x_11, if x_11 were a taxi driver, then x_11 is drinking water can be inferred via the universal biconditional elimination rule.