# Partial Hecke-type operators and their applications

Aykut Ahmet Aygunes and Yilmaz Simsek*

Author Affiliations

Department of Mathematics, Faculty of Science, Akdeniz University, Campus, Antalya, 07058, Turkey

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Boundary Value Problems 2013, 2013:46  doi:10.1186/1687-2770-2013-46

 Received: 14 November 2012 Accepted: 22 January 2013 Published: 6 March 2013

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

### Abstract

The aim of this paper is to give not only the matrix representation of partial Hecke-type operators by means of Bernoulli polynomials and Euler polynomials, but also functional equations and differential equations related to partial Hecke-type operators and special polynomials. By using these functional equations and differential equations, we derive some identities associated with special polynomials and partial Hecke-type operators. Moreover, we find several useful identities and relations using the partial Hecke operators.

MSC: 05B20, 11B68, 11F25.

##### Keywords:
Bernoulli polynomial; Euler polynomial; partial Hecke-type operator; total Hecke-type operator; Hurwitz zeta function; partial zeta function

### 1 Introduction

Recently, there have been many applications of Bernoulli polynomials and Euler polynomials in differential equations, in analytic number theory and in engineering. High-order linear differential-difference equations have also been solved in terms of Bernoulli polynomials. These polynomials are also related to several linear operators. In this paper, we investigate and derive several new identities related to the Hecke-type operators and generating functions for special polynomials.

Recently, many authors introduced and investigated the following generating functions which give us the Bernoulli polynomials and the Euler polynomials , respectively:

(1)

and

(2)

For , (1) and (2) are reduced to the generating functions for the Bernoulli numbers and the Euler numbers , respectively (cf.[1-4]), and see also the references cited in each of these earlier works.

The multiplication formulas for the Bernoulli and Euler polynomials are given as follows:

(3)

and for odd m,

(4)

(cf.[5-8]), and see also the references cited in each of these earlier works.

The Bernoulli polynomials satisfy the following well-known identity:

where m and n are positive integers (cf.[5,9,10]).

Bayad et al. [11] introduced and systematically studied the following family of partial Hecke-type operators on .

Throughout this paper, we use the following notations: . Let and .

For fixed and , we have

where

Lemma 1.1 [[11], p.114, Lemma 1]

For anysuch that, we have the following properties:

(i) preserves the degree in.

(ii) By induction,

where

(iii) For any, letbe the canonical ℂ-basis of

Then the matrixcorresponding to the operator (restricted to) in the basisis represented by:

(5)

for all.

(iv) Letsuch that, then

Consequently, for a given integern, there is only one monic polynomialwith degreeninxsatisfying the functional equation (6).

The operator satisfies the following equation:

(6)

For , from (6) and Lemma 1.1, we know that is a monic polynomial (cf.[11]).

Remark 1.2 Equations (3) and (4) are closely related to the functional equation of (6). For and , equation (6) is reduced to and , respectively. For fixed , we know that there is only one monic polynomial satisfying (6) by Lemma 1.1, and there already exist the functional equations as (3) and (4).

The total Hecke-type operators, associated with partial Hecke-type operators, are defined by Bayad et al. [[11], p.112, Eq. (1.6)] as follows:

Theorem 1.3[11]

Polynomialsare eigenfunctions for the operatorswith eigenvalues, that is,

whereis the Hurwitz zeta function defined by

### 2 Differential equations related to the partial Hecke-type operators and special polynomials

In this section, we derive some ordinary and partial differential equations not only for a generating function, but also for partial Hecke-type operators. We also give a functional equation for the generating function. We set

We now give an explicit formula of the generating function as follows.

Theorem 2.1[11]

Generating functions for the polynomialsare given by

The polynomials are the so-called Bernoulli-Euler-type polynomials.

We derive the following partial differential equation for as follows:

(7)

Theorem 2.2Let. Then

where.

Proof By using (7), for , we obtain

(8)

Therefore, by comparing the coefficients of on both sides of equation (8), we have the desired result.

For , we apply the same process. So, we omit it. □

We set the following differential equation:

(9)

Theorem 2.3

Proof We make some arrangement (9) and obtain

Therefore,

From the above equation, we get

By comparing the coefficients of on both sides of the above equation, we have the desired result. □

Remark 2.4 In Theorem 2.3, we obtain a convolution formula for the polynomials . If we substitute into Theorem 2.3, then we get a convolution formula for the Eulerian-type numbers (cf.[10,13]).

Higher-order partial differential equation for is given by the following theorem.

Theorem 2.5Letand. Then

where

Proof Taking vth derivative of the operator , with respect to x, we obtain the following higher-order partial differential equation:

Using Theorem 2.2, we get

Thus, we get the desired result. □

### 3 Matrix representations of partial Hecke-type operators

In this section, we give some numerical examples for the matrix representations of the operator . For the basis , our matrix representations contain Bernoulli polynomials and Euler polynomials for the operators and , respectively. Therefore, we need the following lemmas.

Lemma 3.1Letand. Then

Lemma 3.2Letand. Then

Proofs of Lemma 3.1 and Lemma 3.2 have been given by many authors (among others) (cf.[2,4,8,10]).

In a special case, substituting into (iii) in Lemma 1.1 and using Lemma 3.1, we get

According to the above equation, we are ready to give the main result of this section by the following theorem.

Theorem 3.3The matrixcorresponding to the operator (restricted to) in the basisis represented by Bernoulli polynomials as follows:

Setting (iii) in Lemma 1.1 and using Lemma 3.2, we obtain

If , then we obtain another main result by the following theorem.

Theorem 3.4Letabe an odd number. The matrixcorresponding to the operator (restricted to) in the basisis represented by Euler polynomials as follows:

### 4 Some applications of total Hecke-type operators

In this section, we give some applications related to eigenvalues for the total Hecke-type operators of and . We derive many new identities which are related not only to the total Hecke-type operators, but also to the Riemann zeta function, the Hurwitz zeta function, Bernoulli and Euler numbers, Euler identities and the convolution of Bernoulli and Euler numbers and polynomials.

Throughout this section, we use the following notation:

The partial zeta function is defined by

where , and () (cf.[4,8,10,12,14]).

Theorem 4.1The polynomialsare eigenfunctions for the operatorswith eigenvalues, that is,

whereis a partial zeta function.

Proof

Therefore,

Substituting , and into the above equation, after using Theorem 1.3, we arrive at the desired result. □

Theorem 4.2Letwith. Then we have

(10)

Proof Putting in Theorem 1.3 and using

we have

(11)

We recall from the definition of and that we have

(12)

(cf. [[10], p.96]). Combining (11) and (12), we get

(13)

If we replace n by 2n in the above equation, we obtain

(14)

From the work of Srivastava and Choi [[4], p.98], we recall that

(15)

where with and

(16)

By substituting (15) and (16) into (14), after some elementary calculations, we arrive at the desired result. □

Theorem 4.3Let. Then

(17)

Proof Combining (14) and (16), we easily complete the proof of the theorem, that is,

□

By using (10) and (17), we obtain a convolution formula (Euler identity) for Bernoulli numbers.

Theorem 4.4Let. Then

(18)

Proof Since the left-hand sides of (10) and (17) are equal, the right-hand sides of (10) and (17) must be equal. Thus, we obtain

After some elementary calculation in the above equation, we get the desired result. □

Observe that the proof of (18) is also given in [4].

Theorem 4.5Let. Then

Proof For all , we have

(19)

(cf. [[4], p.131]). By using (14) and (19), we obtain

Thus, the proof is completed. □

Theorem 4.6Let. Then we have

(20)

Proof Consider that n is replaced by in (13), we have

(21)

For all , one can easily get

(22)

(cf. [[4], p.99, Eq. (21)]). Hence, we have

Thus, the proof is completed. □

Theorem 4.7Let. Then we have

(23)

Proof Note that, for all , we have

(24)

(cf. [[4], p.99, Eq. (22)]). By using (21) and (24), we have

Thus, the proof is completed. □

Theorem 4.8Let. Then

Proof Substituting into Theorem 1.3 and by , we have

(25)

If n is replaced by 2n in the above equation, we get

(26)

By using (16), we have

(27)

Thus, the proof is completed. □

Theorem 4.9Letwith. Then we have

Proof By using (26), (15) and (16), we have

Thus, the proof is completed. □

Theorem 4.10Let. Then

Proof By using (26) and (19), we have

Thus, the proof is completed. □

Theorem 4.11Let. Then

(28)

Proof By replacing n by in (25), we have

(29)

By substituting (29) into (22), we get

Thus, the proof is completed. □

Theorem 4.12Let. Then we have

(30)

Proof By using (29) and (24), we have

Thus, the proof is completed. □

By comparing (20) and (23) or (28) and (30), we arrive at the following result.

Corollary 4.13

### Competing interests

The authors declare that they have no competing interests.

### Authors’ contributions

All authors completed the paper together. All authors read and approved the final manuscript.

### Acknowledgements

Dedicated to Professor Hari M Srivastava.

All authors are partially supported by Research Project Offices Akdeniz Universities. We would like to thank the referees for their valuable comments.

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