Actuarial assumptions

(a) Notwithstanding any provision in this chapter to the contrary, the board may approve the effect of the post retirement allowance under section 88-90, or of any other mandatory fixed scheduled increase in the benefits payable under part II, VII, or VIII, as an actuarial assumption for the purpose of determining the value of the options available under sections 88-83, 88-283, and 88-333. (b) Subject to the recommendation of the actuary appointed under section 88-29, the board may adopt, by motion at any duly noticed meeting of the board, actuarial tables, factors, and assumptions for the purposes of parts II, VII, and VIII. The tables, factors, and assumptions that are used to compute benefits shall be in writing and certified by the executive director.