theorem Th21:
  W-bound C <= E-bound C
proof
A1: N-min C in C by Th11;
  then
A2: (N-min C)`1 <= E-bound C by PSCOMP_1:24;
  W-bound C <= (N-min C)`1 by A1,PSCOMP_1:24;
  hence thesis by A2,XXREAL_0:2;
end;
