It shall be an unfair labor practice for a public employer:

(1) To interfere with, restrain, or coerce public employees in the exercise of their rights guaranteed by this chapter;

(2) To control, dominate, or interfere with a bargaining representative;

(3) To discriminate against a public employee who has filed an unfair labor practice charge;

(4) To refuse to engage in collective bargaining with the certified exclusive bargaining representative.