theorem
  Gen w,y implies DTrSpace(V,w,y) is MidOrdTrapSpace
proof
  set X = DTrSpace(V,w,y);
  assume
A1: Gen w,y;
  X is MidOrdTrapSpace-like
  by Lm27,Lm28,Lm29,Lm30,Lm31,A1,Lm32,Lm33,Lm34,Lm35,Lm22,Lm23,Lm24,Lm25,Lm26;
  hence thesis;
end;
