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114   4. Particular Determinants

          Proof of (F). Denote the sum by S and apply the Hankelian relation
          φ r+s−3 = a r,s−1 = a r−1,s .

                    n           n             n           n

               S =    (s − 1)A sj  a r,s−1 A +  (r − 1)A ir  a r−1,s A sj
                                         ir
                   s=1         r=1           r=1         s=1
                    n                  n

                 =    (s − 1)A δ s−1,i +  (r − 1)A δ r−1,j .
                             sj
                                                 ir
                   s=1                r=1
          The proof of (F) follows. Equation (E) is proved in a similar manner.

          Exercises

          Prove the following:

          1.        A ij,pq  =0.
             p+q=m+2
             2n−2

          2.     φ m       A ip,jq =(n − 1)A ij .
             m=0    q+q=m+2
             2n−2
                                       2
          3.     mφ m        A ip,jq =(n − n − i − j +2)A ij .
             m=1     p+q=m+2
             2n−2

          4.     φ m        A ijp,hkq  = nA ij,hk .
             m=0    p+q=m+2
             2n−2
                                         2
          5.     mφ m        A ijp,hkq  =(n − n − i − j − h − k − 4)A ij,hk .
             m=1     p+q=m+2
             2n−2

          6.     mφ m−1        A ijp,hkq
             m=1        p+q=m+2
             = iA i+1,j;hk  + jA i,j+1;hk  + hA ij;h+1,k  + kA ij;h,k+1 .
             2n−2

          7.             φ p+r−1 φ q+r−1 A pq  = φ 2r ,  0 ≤ r ≤ n − 1.
             m=0 p+q=m+2
             2n−2

          8.     m         φ p+r−1 φ q+r−1 A pq  =2rφ 2r ,  0 ≤ r ≤ n − 1.
             m=1   p+q=m+2
          9. Prove that

                           n−1        n

                              rA r+1,j   φ m+r−2 A im  = iA i+1,j
                           r=1       m=1
             by applying the sum formula for Hankelians and, hence, prove (F 1 )
             directly. Use a similar method to prove (E 1 ) directly.
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