theorem
  1 <= j & j <= len Gauge(T,n) implies Gauge(T,n)*(2,j)`1 = W-bound T
proof
  set G = Gauge(T,n);
  set W = W-bound T, S = S-bound T, E = E-bound T, N = N-bound T;
  assume that
A1: 1 <= j and
A2: j <= len Gauge(T,n);
A3: len G = width G by Def1;
  len G >= 4 by Th10;
  then 2 <= len G by XXREAL_0:2;
  then [2,j] in Indices G by A1,A2,A3,MATRIX_0:30;
  then G*(2,j) = |[W+((E-W)/(2|^n))*(2-2), S+(N-S)/(2|^n)*(j-2)]| by Def1;
  hence thesis by EUCLID:52;
end;
