reserve r,t for Real;
reserve i for Integer;
reserve k,n for Nat;
reserve p for Polynomial of F_Real;
reserve e for Element of F_Real;
reserve L for non empty ZeroStr;
reserve z,z0,z1,z2 for Element of L;

theorem Th23:
  <%z0,z1,z2%>.2 = z2
  proof
    dom(0_.L+*(0,z0)+*(1,z1)) = dom(0_.L+*(0,z0)) by FUNCT_7:30
    .= dom 0_.L by FUNCT_7:30
    .= NAT by FUNCOP_1:13;
    hence <%z0,z1,z2%>.2 = z2 by FUNCT_7:31;
  end;
