The legislature sets forth as retirement policy and intent:
(1) The retirement systems of the state shall provide similar benefits wherever possible.
(2) Persons hired into eligible positions shall accrue service credit for all service rendered.
(3) The calculation of benefits shall be done in such a manner as to prevent the arithmetic lowering of benefits.
(4) Liberalization of the granting of service credit shall not jeopardize part-time employment of retirees in ineligible positions.