reflexivity.
Qed.

Theorem hF_PRF :
PRF_Advantage ({0, 1}^(c + k)) ({0, 1}^c) hF _ _ A <=
PRF_Advantage ({0, 1}^c) ({0, 1}^c) h _ _ PRF_h_A +
Adv_WCR _ _ F (Rnd k) au_F_A.