Abstract
The main aim of this present paper is to present certain generating functions of some hypergeometric functions in four variables by using the integral and symbolic representations for these quadruple functions. A few interesting special cases have also been considered.
1. Introduction
Several families of generating functions have been established in diverse ways. These are playing important roles in the theory of special functions of applied mathematics and mathematical physics. One can refer the extensive work of Srivastava and Manocha 1 for a systematic introduction to, and several interesting and useful applications of the various methods of obtaining linear, bilinear, bilateral or mixed multilateral generating functions for a fairly wide variety of sequences of hypergeometric functions and polynomials in one, two or more variables, among much abundant literature. In fact, a remarkable large number of generating functions involving a variety of hypergeometric functions have been developed by many authors such as 2, 3, 4, 5, 6.
Bin-Saad and Younis introduced in 7 thirty new quadruple hypergeometric series, ten of them defined below
 | (1) |
 | (2) |
 | (3) |
 | (4) |
 | (5) |
 | (6) |
 | (7) |
 | (8) |
 | (9) |
 | (10) |
Here
is the Pochhammer symbol which defined as
with the assumed 
It may be recalled the Laplace integral representations of the above functions, see e.g. 8, 9, 10, 11 respectively, as below
 | (11) |
 | (12) |
 | (13) |
 | (14) |
 | (15) |
 | (16) |
 | (17) |
 | (18) |
 | (19) |
 | (20) |
where
and
denote the confluent hypergeometric functions 12.
The aim of this paper is to investigate the various generating functions for the quadruple hypergeometric functions
In Section 2, our main generating functions are obtained with the help of integral representations of Laplace-type. In Section 3, we introduce symbolic representations for the functions. The aim of Section 4 is to use symbolic representations to derive a number of generating functions.
2. Generating Functions via Laplace Integral Representations
Here, in this Section, we used the Laplace integral representations for the hypergeometric series of four variables defined in pervious Section to determine generating functions which are listed in the form of following relations (21) to (34):
 | (21) |
 | (22) |
 | (23) |
 | (24) |
 | (25) |
 | (26) |
 | (27) |
 | (28) |
 | (29) |
 | (30) |
 | (31) |
 | (32) |
 | (33) |
 | (34) |
where
is the Horn function defined in 12,
and
are the Lauricella functions defined in 13,
is the Srivastava function defined in 12.
and
are the Exton functions defined in 14 and
is the Sharma and Parihar function defined in 15.
Proof. To prove (21), for convenience and simplicity, by denoting the left-hand side of (21) with
and using (11), we have
Using the Kummer's transformation (see 16)
after a little simplification, we get
Using the following well-known formula (see 16, 17)
after a little simplification, we easily arrive at the right-hand side of (21). This completes the proof of (21). The proof of the relations (22) to (34) runs in same way.
If we take
in (32) , we shall obtain the following relation:
which, for
yields the well-known result (see 12).
By setting
in (22) and (33), we have the following generating relations:
where
is quadruple hypergeometric series defined by Bin-Saad and Younis (see 9 and 7).
which, for
we obtain new connection between Srivastava function
and Sharma and Parihar function 
3. Symbolic Representations
In this section, we consider the symbolic images for the quadruple functions (1) - (10). Our results presented here are obtained with the help of the following operator formulas:
 | (35) |
 | (36) |
where the operators
and
are the derivative operator and the inverse of the derivative, respectively, (see 18). Now, we introduce certain operational representations involving quadruple functions as below:
 | (37) |
 | (38) |
 | (39) |
 | (40) |
 | (41) |
 | (42) |
 | (43) |
 | (44) |
 | (45) |
 | (46) |
where
is the exponential expansion defined by (see 16)
 | (47) |
Proof. To prove formula (37), denote, for convenience, the left-hand side of assertion (37) by
Then by the exponential expansion (47) and binomial theorem, we have
Using (35) and (36) and in view of the definition (1), we obtain the desired result (37). The proofs of formulas (38) to (46) run parallel to that of formula (37), so are skipped details.
If we take
in (40) and (41), we get operational representations involving Srivastava's function
(see 12). Relation (44) with
yield the Bin-Saad's and Maisoon's results 19.
4. Generating Functions via Symbolic Representations
In this section, we establish some generating relations by using the symbolic images obtained in previous section. Following are these generating relations:
 | (48) |
 | (49) |
 | (50) |
 | (51) |
 | (52) |
 | (53) |
 | (54) |
 | (55) |
 | (56) |
 | (57) |
Proof. To prove relation (48), taking
in (37) and multiplying both the sides with
we obtain
and then taking the double sum of both sides we get
Now, by using the definition (47), then, after some simplification gives the result. In a similar manner, one can prove the relations (49) to (57).
If we choose
in (54) and (57), and simplifying, we have the following new generating functions:
which, for
we have generating functions involving Appell's series 12 
which, for
after a little simplification, we have interesting result
where
is the Gaussian hypergeometric function (see 12).
5. Conclusion
Based on the integral and operational representations for the hypergeometric functions of four variables defined in (1) to (10), we established several generating functions for these quadruple functions. Some particular cases and the consequences of our main results are also considered. We concluded this investigation by remarking that the scheme suggested in the derivation of the results can be applied to find other new generating functions for other quadruple hypergeometric functions and study their special cases.
Conflict of Interest
The authors have no competing interests.
References
[1] | Srivastava, M. H and Manocha, H. A., Treatise on Generating Functions. Halsted Press, Bristone, London, New York and Toronto, 1985. |
| In article | |
|
[2] | Agarwal, P., Chand, M and Purohit, S. D., A note on generating functions involving the generalized Gauss hypergeometric function. National Acad. Sci. Lett., 3, 457-459, 2014. |
| In article | View Article |
|
[3] | Bin-Saad, M. G and Younis, J. A., Certain generating functions of some quadruple hypergeometric series. Eurasian Bulletin Math., 2, 56-62, 2019. |
| In article | |
|
[4] | Desale, B. S and Qashash, G. A., Generating functions of special triple hypergeometric functions. International Mathematical Forum, 9, 1677-1693, 2014. |
| In article | View Article |
|
[5] | Liu, H and Wang, W., Some generating relations for extended Appell’s and Lauricella’s hypergeometric functions. Rocky Mountain J. Math., 44, 1987-2007, 2014. |
| In article | View Article |
|
[6] | Singh, M., Pundhir, S and Singh, M. P., Generating function of certain hypergeometric functions by means of fractional calculus. International J. Comput. Eng. Res. (IJCER), 11, 40-47, 2017. |
| In article | |
|
[7] | Bin-Saad, M. G and Younis, J. A., On connections between certain class of new quadruple and known triple hypergeometric series. Tamap Journal of Mathematics and Statistics, Volume 2019. |
| In article | |
|
[8] | Bin-Saad, M. G and Younis, J. A., Certain quadruple hypergeometric series and their integral representations. Appl. Appl. Math., 14, 1085-1098, 2019. |
| In article | |
|
[9] | Bin-Saad, M. G and Younis, J. A., Certain integrals associated with hypergeometric functions of four variables. Earthline J. Math. Sci., 2, 325-341, 2019. |
| In article | View Article |
|
[10] | Bin-Saad, M. G and Younis, J. A., Certain integral representations of some quadruple hypergeometric series. Palestine J. Math., 9, 132-141, 2020. |
| In article | |
|
[11] | Bin-Saad, M. G and Younis, J. A., Some integrals connected with a new quadruple hypergeometric series, Universal J. Math. Appl., 3, 19-27, 2020. |
| In article | View Article |
|
[12] | Srivastava, M. H and Karlsson, P. W., Multiple Gaussian Hypergeometric Series. Ellis Horwood Lt1., Chichester, 1984. |
| In article | |
|
[13] | Lauricella, G., Sull funzioni ipergeometric a pi variabili. Rend. Cric. Mat. Palermo, 7, 111-158, 1893. |
| In article | View Article |
|
[14] | Exton, H., Hypergeometric functions of three variables. J. Indian Acad. Math., 4, 113-119, 1982. |
| In article | |
|
[15] | Sharma, C and Parihar, C. L., Hypergeometric functions of four variables (I). J. Indian Acad. Math., 11, 121-133, 1989. |
| In article | |
|
[16] | Erdélyi, A., Magnus, W., Oberhettinger, F and Tricomi, F. G., Higher Transcendental Functions. Vol. I, McGraw-Hill Book Company, New York, Toronto and London, 1953. |
| In article | |
|
[17] | Rainville, E. D., Special Functions. The Macmillan Company: New York, NY, USA, 1960; Reprinted by Chelsea Publishing Company, Bronx, NY, USA, 1971. |
| In article | |
|
[18] | Miller, K. S and Ross, B., An Introduction to Fractional Calculus and Fractional Differential Equations. Wiley, New York, 1993. |
| In article | |
|
[19] | Bin-Saad, M. G and Hussein, M. A., Operational images and relations of two and three variable hypergeometric series. J. Progr. Res. Math., 2, 39-46, 2015. |
| In article | |
|
Published with license by Science and Education Publishing, Copyright © 2020 Jihad A. Younis, Maged G. Bin-Saad and Kottakkaran S. Nisar
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Cite this article:
Normal Style
Jihad A. Younis, Maged G. Bin-Saad, Kottakkaran S. Nisar. Certain Generating Functions Involving Some Hypergeometric Series of Four Variables by Means of Operational Representations. Turkish Journal of Analysis and Number Theory. Vol. 8, No. 6, 2020, pp 97-106. https://pubs.sciepub.com/tjant/8/6/1
MLA Style
Younis, Jihad A., Maged G. Bin-Saad, and Kottakkaran S. Nisar. "Certain Generating Functions Involving Some Hypergeometric Series of Four Variables by Means of Operational Representations." Turkish Journal of Analysis and Number Theory 8.6 (2020): 97-106.
APA Style
Younis, J. A. , Bin-Saad, M. G. , & Nisar, K. S. (2020). Certain Generating Functions Involving Some Hypergeometric Series of Four Variables by Means of Operational Representations. Turkish Journal of Analysis and Number Theory, 8(6), 97-106.
Chicago Style
Younis, Jihad A., Maged G. Bin-Saad, and Kottakkaran S. Nisar. "Certain Generating Functions Involving Some Hypergeometric Series of Four Variables by Means of Operational Representations." Turkish Journal of Analysis and Number Theory 8, no. 6 (2020): 97-106.