let C be compact non horizontal non vertical Subset of (TOP-REAL 2); :: thesis: for n being Nat holds len (Lower_Seq C,n) = ((len (Rotate (Cage C,n),(W-min (L~ (Cage C,n))))) - ((E-max (L~ (Cage C,n))) .. (Rotate (Cage C,n),(W-min (L~ (Cage C,n)))))) + 1
let n be Nat; :: thesis: len (Lower_Seq C,n) = ((len (Rotate (Cage C,n),(W-min (L~ (Cage C,n))))) - ((E-max (L~ (Cage C,n))) .. (Rotate (Cage C,n),(W-min (L~ (Cage C,n)))))) + 1
E-max (L~ (Cage C,n)) in rng (Cage C,n) by SPRECT_2:50;
then E-max (L~ (Cage C,n)) in rng (Rotate (Cage C,n),(W-min (L~ (Cage C,n)))) by FINSEQ_6:96, SPRECT_2:47;
hence len (Lower_Seq C,n) = ((len (Rotate (Cage C,n),(W-min (L~ (Cage C,n))))) - ((E-max (L~ (Cage C,n))) .. (Rotate (Cage C,n),(W-min (L~ (Cage C,n)))))) + 1 by FINSEQ_5:53; :: thesis: verum