theorem
f=v & g=u implies f+g=v+u
proof
   reconsider v2=v, u2=u as VECTOR of RLSp_LpFunct(M,k) by TARSKI:def 3;
   assume A1: f=v & g=u;
   v+u=v2+u2 by LPSPACE1:4;
   hence v+u = f+g by Th29,A1;
end;
