reserve n for Nat,
  k for Integer;
reserve p for polyhedron,
  k for Integer,
  n for Nat;

theorem Th70:
  for c being Element of dim(p)-chain-space(p), x being Element of
  dim(p)-polytopes(p) st c = {p} holds c@x = 1.Z_2
proof
A1: dim(p)-polytopes(p) = {p} by Def5;
  let c be Element of dim(p)-chain-space(p), x be Element of dim(p)-polytopes(
  p);
  assume c = {p};
  hence thesis by A1,BSPACE:def 3;
end;
