reserve a,b,c,d,e,f for Real,
        g           for positive Real,
        x,y         for Complex,
        S,T         for Element of REAL 2,
        u,v,w       for Element of TOP-REAL 3;
reserve a,b,c for Element of F_Real,
          M,N for Matrix of 3,F_Real;
reserve D        for non empty set;
reserve d1,d2,d3 for Element of D;
reserve A        for Matrix of 1,3,D;
reserve B        for Matrix of 3,1,D;

theorem Th25:
  <* <* d1 *> ,<* d2 *> ,<* d3 *> *> is Matrix of 3,1,D
  proof
    reconsider p = <* d1 *>, q = <* d2 *>, r = <* d3 *> as FinSequence of D;
    len p = 1 & len q = 1 & len r = 1 by FINSEQ_1:40;
    hence thesis by MATRIXR2:34;
  end;
