49 research outputs found
Hierarchical Dobinski-type relations via substitution and the moment problem
We consider the transformation properties of integer sequences arising from
the normal ordering of exponentiated boson ([a,a*]=1) monomials of the form
exp(x (a*)^r a), r=1,2,..., under the composition of their exponential
generating functions (egf). They turn out to be of Sheffer-type. We demonstrate
that two key properties of these sequences remain preserved under
substitutional composition: (a)the property of being the solution of the
Stieltjes moment problem; and (b) the representation of these sequences through
infinite series (Dobinski-type relations). We present a number of examples of
such composition satisfying properties (a) and (b). We obtain new Dobinski-type
formulas and solve the associated moment problem for several hierarchically
defined combinatorial families of sequences.Comment: 14 pages, 31 reference
Sheffer and Non-Sheffer Polynomial Families
By using the integral transform method, we introduce some non-Sheffer polynomial sets. Furthermore, we show how to compute the connection coefficients for particular expressions of Appell polynomials
Josef Meixner: his life and his orthogonal polynomials
This paper starts with a biographical sketch of the life of Josef Meixner.
Then his motivations to work on orthogonal polynomials and special functions
are reviewed. Meixner's 1934 paper introducing the Meixner and
Meixner-Pollaczek polynomials is discussed in detail. Truksa's forgotten 1931
paper, which already contains the Meixner polynomials, is mentioned. The paper
ends with a survey of the reception of Meixner's 1934 paper.Comment: v4: 18 pages, generating function for Krawtchouk polynomials on p.10
correcte
Power Series Composition and Change of Basis
Efficient algorithms are known for many operations on truncated power series
(multiplication, powering, exponential, ...). Composition is a more complex
task. We isolate a large class of power series for which composition can be
performed efficiently. We deduce fast algorithms for converting polynomials
between various bases, including Euler, Bernoulli, Fibonacci, and the
orthogonal Laguerre, Hermite, Jacobi, Krawtchouk, Meixner and
Meixner-Pollaczek
Repeated derivatives of hyperbolic trigonometric functions and associated polynomials
Elementary problems as the evaluation of repeated derivatives of ordinary transcendent functionscan usefully be treated with the use of special polynomials and of a formalism borrowed from combinatorial analysis. Motivated by previous researches in this field, we review the results obtained by other authors and develop a complementary point of view for the repeated derivatives of sec(.), tan(.) and for their hyperbolic counterparts