reserve q,r,c,c1,c2,c3 for Quaternion;
reserve x1,x2,x3,x4,y1,y2,y3,y4 for Real;
reserve z for Element of R_Quaternion;

theorem
  (1.R_Quaternion)" = 1.R_Quaternion
proof
  1q"= 1q by Th33
    .= 1.R_Quaternion by Def10;
  hence thesis by Def10;
end;
