reserve V for RealLinearSpace;
reserve p,q,u,v,w,y for VECTOR of V;
reserve a,b,c,d for Real;

theorem Th6:
  (a<>0 & a*u=v implies u=a"*v) & (a<>0 & u=a"*v implies a*u=v)
proof
  now
    assume a<>0 & u=a"*v;
    hence v=(a")"*u by Th5,XCMPLX_1:202
      .=a*u;
  end;
  hence thesis by Th5;
end;
