fact: Fixpoint sum_nat_f_O (f:nat -> nat) (n:nat) : nat := match n with | O => f 0%nat | S n' => (sum_nat_f_O f n' + f (S n'))%nat end.
imports: ArithRing Rdefinitions Raxioms RIneq Rpow_def R_Ifp Rbasic_fun R_sqr SplitAbsolu SplitRmult ArithProp Zpower Ztac