ON SOME ALTERNATIVE CHARACTERIZATIONS OF RIORDAN ARRAYS

We give several new characterizations of Riordan Arrays, the most impo rtant of which is: if {d(n,k)}(n,k epsilon N) is a lower triangular ar ray whose generic element d(n,k) linearly depends on the elements in a well-defined though large area of the array, then {d(n,k)}(n,k epsilo n N) is Riordan. We also provide some applications of these characteri zations to the lattice path theory.