let L be Z_Lattice; for v being Vector of L holds SumSc (v,(ZeroLC L)) = 0. F_Real
let v be Vector of L; SumSc (v,(ZeroLC L)) = 0. F_Real
consider F being FinSequence of L such that
A1:
( F is one-to-one & rng F = Carrier (ZeroLC L) & SumSc (v,(ZeroLC L)) = Sum (ScFS (v,(ZeroLC L),F)) )
by defSumSc;
F = {}
by A1, VECTSP_6:def 3;
then
len (ScFS (v,(ZeroLC L),F)) = 0
by defScFS;
hence
SumSc (v,(ZeroLC L)) = 0. F_Real
by A1, RLVECT_1:75; verum