Research Article
Arbitrary Order Fractional Difference Operators with Discrete
Exponential Kernels and Applications
Thabet Abdeljawad,
1
Qasem M. Al-Mdallal,
2
and Mohamed A. Hajji
2
1
Department of Mathematics and Physical Sciences, Prince Sultan University, P.O. Box 66833, Riyadh 11586, Saudi Arabia
2
Department of Mathematical Sciences, United Arab Emirates University, P.O. Box 17551, Al Ain, Abu Dhabi, UAE
Correspondence should be addressed to Tabet Abdeljawad; tabdeljawad@psu.edu.sa
Received 3 April 2017; Accepted 25 May 2017; Published 21 June 2017
Academic Editor: Garyfalos Papashinopoulos
Copyright © 2017 Tabet Abdeljawad et al. Tis is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly
cited.
Recently, Abdeljawad and Baleanu have formulated and studied the discrete versions of the fractional operators of order 0<≤1
with exponential kernels initiated by Caputo-Fabrizio. In this paper, we extend the order of such fractional diference operators to
arbitrary positive order. Te extension is given to both lef and right fractional diferences and sums. Ten, existence and uniqueness
theorems for the Caputo (CFC) and Riemann (CFR) type initial diference value problems by using Banach contraction theorem are
proved. Finally, a Lyapunov type inequality for the Riemann type fractional diference boundary value problems of order 2<≤3
is proved and the ordinary diference Lyapunov inequality then follows as tends to 2 from right. Illustrative examples are discussed
and an application about Sturm-Liouville eigenvalue problem in the sense of this new fractional diference calculus is given.
1. Introduction
In the last few decades, the continuous and discrete fractional
diferential equations have received considerable interest due
to their importance in many scientifc felds; see, by way of
example not exhaustive enumeration, [1–7].
In [8], the authors introduced a fractional derivative
with an exponential kernel which tends to the ordinary
derivative as tends to 1. More properties of this fractional
derivative have been studied in [9], where the correspondent
fractional integral operator was formulated. Ten, the authors
in [7] defned the lef and right fractional derivatives with
exponential kernel in the Riemann sense and formulated the
right fractional derivatives in the sense of Caputo-Fabrizio
with complete investigation to the correspondent fractional
integrals and all the discrete versions with integration and
summation by parts applied in the fractional and discrete
fractional variational calculus. Ten, very recently, the same
authors proved an interesting monotonicity result in the sense
of this new fractional diference calculus in [10].
In the same direction, for the purpose of providing
more fractional derivatives with diferent nonsingular ker-
nels, the authors in [11] defned a fractional operator with
Mittag-Lefer kernel and in [12, 13] the complete details and
discrete versions have been studied. Te exponential kernel
fractional derivatives and hence their discrete counterparts
are quite diferent from the Mittag-Lefer kernel fractional
operators. For example, the integral operator corresponding
to exponential kernel fractional derivatives consists of a mul-
tiple of the function added to a multiple of the integration of
, whereas the Mittag-Lefer kernel correspondent integral
operator consists of a multiple of and a Riemann-Liouville
fractional integral of the same order. Also, the monotonicity
coefcient of the CFR fractional diference operator of order
0<≤1 is as shown in [10], whereas for the discrete
Mittag-Lefer CFR operator is
2
as proven in [14].
Motivated, by what we mentioned above, we extend
the order of fractional diference type operators with dis-
crete exponential kernels to arbitrary positive order, prove
existence and uniqueness theorems for the fractional initial
value diference problems, and fnally prove a Lyapunov type
inequality for the CFR fractional diference operators of order
2<≤3. Te ordinary discrete Lyapunov inequality is then
confrmed as tends to 2 from the right not as in the case of
the classical fractional diference as tends to 2 from the lef
[15]. For various fractional Lyapunov extensions we refer, for
Hindawi
Discrete Dynamics in Nature and Society
Volume 2017, Article ID 4149320, 8 pages
https://doi.org/10.1155/2017/4149320