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, if x_11 takes a plane, then x_11 is reading a book. For all x_11, x_11 is not a scientist. For all x_11, x_11 will take a plane or x_11 will write a letter. For all x_11, if x_11 writes a letter, then x_11 is reading a book. For all x_11, x_11 will play tennis or x_11 is a politician. For all x_11, x_11 is a scientist if and only if x_11 will play tennis.
For all x_11, x_11 will read a book can be inferred via the universal disjunction elimination rule. For all x_11, if x_11 were a scientist, then x_11 is playing tennis can be inferred via the universal biconditional elimination rule. For all x_11, if x_11 plays tennis, then x_11 is a scientist can be inferred via the universal biconditional elimination rule. For all x_11, x_11 will not play tennis can be inferred via the universal biconditional elimination rule.