unfold FNodd, FNeven, FNSucc in |- *.
intros p H' H'0.
rewrite FcanonicFnormalizeEq; auto with float arith.
apply FevenSuc; auto.
Qed.

Theorem FNevenPred :
forall p : float,
Fbounded b p -> FNodd p -> FNeven (FNPred b radix precision p).