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, x_7 is curious or x_7 will not write a letter. For all x_7, x_7 is not a politician. For all x_7, x_7 is a politician if and only if x_7 is curious.
For all x_7, if x_7 writes a letter, then x_7 is curious can be inferred via the universal rewriting rule. For all x_7, if x_7 were a politician, then x_7 is curious can be inferred via the universal biconditional elimination rule. For all x_7, if x_7 were curious, then x_7 is a politician can be inferred via the universal biconditional elimination rule. For all x_7, x_7 is not curious can be inferred via the universal biconditional elimination rule.