Lemma expf_B0_CS_2_b_ind:forall (m:fmap)(x z:dart)(i:nat), inv_hmap m -> succ m zero x -> exd m z -> let x0 := cA m zero x in let x_1:= cA_1 m one x in let xb0:= bottom m zero x in let xh0:= top m zero x in let xh0_1:= cA_1 m one xh0 in ~expf m x0 xb0 -> let t:=Iter (cF m) i z in ~expf m x_1 z -> ~expf m xh0_1 z -> expf (B m zero x) z t.