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Hermite–Hadamard-type inequalities for the interval-valued approximately h-convex functions via generalized fractional integrals
Journal of Inequalities and Applications volume 2020, Article number: 222 (2020)
Abstract
In this paper, we present a new definition of interval-valued convex functions depending on the given function which is called “interval-valued approximately h-convex functions”. We establish some inequalities of Hermite–Hadamard type for a newly defined class of functions by using generalized fractional integrals. Our new inequalities are the extensions of previously obtained results like (D.F. Zhao et al. in J. Inequal. Appl. 2018(1):302, 2018 and H. Budak et al. in Proc. Am. Math. Soc., 2019). We also discussed some special cases from our main results.
1 Introduction
The inequality discovered by Hermite and Hadamard (see [3], [4, pp. 137]) is one of the best-established inequalities in the theory of convex functions with a geometrical interpretation and many applications. These inequalities state that, if \(f:I\rightarrow \mathbb{R}\) is a convex function on the interval I of real numbers and \(a,b\in I\) with \(a< b\), then
Both inequalities in (1.1) hold in the reversed direction if f is concave. We note that Hermite–Hadamard inequality may be regarded as a refinement of the concept of convexity and it follows easily from Jensen’s inequality. Hermite–Hadamard inequality for convex functions has received renewed attention in recent years and a remarkable variety of refinements and generalizations have been studied; see [5–14] and the references therein.
On the other hand, interval analysis is a particular case of set-valued analysis, which is the study of sets in the spirit of mathematical analysis and general topology. It was introduced as an attempt to handle interval uncertainty that appears in many mathematical or computer models of some deterministic real-world phenomena. An old example of an interval enclosure is Archimedes’ method which is related to computation of the circumference of a circle. In 1966, the first book related to interval analysis was given by Moore who is known as the first user of intervals in computational mathematics; see [15]. After his book, several scientists started to investigate the theory and application of interval arithmetic. Nowadays, because of its applications, interval analysis is a useful tool in the various area which are interested intensely in uncertain data. You can see applications in computer graphics, experimental and computational physics, error analysis, robotics, and many others.
Moreover, several important inequalities (Hermite–Hadamard, Ostrowski, etc.) have been studied for the interval-valued functions in recent years. In [16, 17], Chalco–Cano et al. obtained Ostrowski type inequalities for interval-valued functions by using the Hukuhara derivative for interval-valued functions. In [18], Román-Flores et al. established Minkowski and Beckenbach’s inequalities for interval-valued functions. For the others, see [18–22]. However, inequalities were studied for the more general set-valued maps. For example, in [23], Sadowska gave the Hermite–Hadamard inequality. For other studies, you can see [24, 25].
The purpose of this paper is to complete the Riemann–Liouville integrals for interval-valued functions and to obtain the Hermite–Hadamard inequality via these integrals. Furthermore, Hermite–Hadamard-type inequalities are given using these integrals.
2 Interval calculus
A real valued interval X is a bounded, closed subset of \(\mathbb{R} \) and is defined by
where \(\underline{X}\), \(\overline{X}\in \mathbb{R} \) and \(\underline{X}\leq \overline{X}\). The numbers \(\underline{X}\) and X̅ are called the left and the right endpoints of the interval X, respectively. When \(\overline{X}=\underline{X}=a\), the interval X is said to be degenerate and we use the form \(X=a=[a,a]\). Also, we call X positive if \(\underline{X}>0\) or negative if \(\overline{X}<0\). The set of all closed intervals of \(\mathbb{R} \), and the sets of all closed positive intervals of \(\mathbb{R} \) and closed negative intervals of \(\mathbb{R} \) is denoted by \(\mathbb{R} _{\mathcal{I}}\), \(\mathbb{R} _{\mathcal{I}}^{+}\) and \(\mathbb{R} _{\mathcal{I}}^{-}\), respectively. The Pompeiu–Hausdorff distance between the intervals X and Y is defined by
It is well known that \(( \mathbb{R} _{\mathcal{I}},d ) \) is a complete metric space; see [26].
Now, we give the definitions of basic interval arithmetic operations for the intervals X and Y as follows:
Scalar multiplication of the interval X is defined by
where \(\lambda \in \mathbb{R} \).
The opposite of the interval X is
where \(\lambda =-1\).
The subtraction is given by
In general, −X is not additive inverse for X, i.e. \(X-X\neq 0\).
The definitions of operations lead to a number of algebraic properties which allows \(\mathbb{R} _{\mathcal{I}}\) to be a quasilinear space; see [27]. They can be listed as follows (see [15, 26–29]):
-
(1)
(Associativity of addition) \((X+Y)+Z=X+(Y+Z)\) for all \(X,Y,Z\in \mathbb{R} _{\mathcal{I}}\),
-
(2)
(Additivity element) \(X+0=0+X=0\) for all \(X\in \mathbb{R} _{\mathcal{I}}\),
-
(3)
(Commutativity of addition) \(X+Y=Y+X\) for all \(X,Y\in \mathbb{R} _{\mathcal{I}}\),
-
(4)
(Cancelation law) \(X+Z=Y+Z\Longrightarrow X=Y\) for all \(X,Y,Z\in \mathbb{R} _{\mathcal{I}}\),
-
(5)
(Associativity of multiplication) \((X\cdot Y)\cdot Z=X\cdot (Y\cdot Z)\) for all \(X,Y,Z\in \mathbb{R} _{\mathcal{I}}\),
-
(6)
(Commutativity of multiplication) \(X\cdot Y=Y\cdot X\) for all \(X,Y\in \mathbb{R} _{\mathcal{I}}\),
-
(7)
(Unity element) \(X\cdot 1=1\cdot X\) for all \(X\in \mathbb{R} _{\mathcal{I}}\),
-
(8)
(Associativity law) \(\lambda (\mu X)= ( \lambda \mu ) X\) for all \(X\in \mathbb{R} _{\mathcal{I}}\) and all \(\lambda ,\mu \in \mathbb{R} \),
-
(9)
(First distributivity law) \(\lambda (X+Y)=\lambda X+\lambda Y\) for all \(X,Y\in \mathbb{R} _{\mathcal{I}}\) and all \(\lambda \in \mathbb{R} \),
-
(10)
(Second distributivity law) \((\lambda +\mu )X=\lambda X+\mu X\) for all \(X\in \mathbb{R} _{\mathcal{I}}\) and all \(\lambda ,\mu \in \mathbb{R} \).
Besides these properties, the distributive law is not always valid for intervals. For example, \(X=[1,2]\), \(Y=[2,3]\) and \(Z=[-2,-1]\).
whereas
But this law holds in certain cases. If \(Y\cdot Z>0\), then
Moreover, one of the set properties is the inclusion ⊆ that is given by
Considering together with arithmetic operations and inclusion, one has the following property which is called the inclusion isotone of interval operations:
Let ⊙ be the addition, multiplication, subtraction or division. If X, Y, Z and T are intervals such that
then the following relation is valid:
The following proposition is about scalar multiplication preserving the inclusion.
Proposition 1
Let X, Y be intervals and \(\lambda \in \mathbb{R} \). If \(X\subseteq Y\), then \(\lambda X\subseteq \lambda Y\).
2.1 Integral of interval–valued functions
In this section, the notion of integral is mentioned for interval-valued functions. Before the definition of integral, the necessary concepts will be given as follows:
A function F is said to be an interval-valued function of t on \([a,b]\), if it assigns a nonempty interval to each \(t\in {}[ a,b]\)
A partition of \([ a,b ] \) is any finite ordered subset P having the form
The mesh of a partition P is defined by
We denote by \(P ( [ a,b ] ) \) the set of all partitions of \([ a,b ] \). Let \(P ( \delta , [ a,b ] ) \) be the set of all \(P\in P ( [ a,b ] ) \) such that \(\operatorname{mesh}(P)<\delta \). Choose an arbitrary point \(\xi _{i}\) in the interval \([ t_{i-1},t_{i} ] \), (\(i=1,2,\ldots,n\)) and let us define the sum
where \(F: [ a,b ] \rightarrow \mathbb{R} _{\mathcal{I}}\). We call \(S(F,P,\delta )\) a Riemann sum of F corresponding to \(P\in P ( \delta , [ a,b ] ) \).
Definition 1
A function \(F: [ a,b ] \rightarrow \mathbb{R} _{\mathcal{I}}\) is called interval Riemann integrable (\((IR)\)-integrable) on \([ a,b ]\), if there exists \(A\in \mathbb{R} _{I}\) such that, for each \(\varepsilon >0\), there exists \(\delta >0\) such that
for every Riemann sum S of F corresponding to each \(P\in P ( \delta , [ a,b ] )\) and independent from choice of \(\xi _{i}\in [ t_{i-1},t_{i} ] \) for all \(1\leq i\leq n\). In this case, A is called the \((IR)\)-integral of F on \([ a,b ] \) and is denoted by
The collection of all functions that are \((IR)\)-integrable on \([ a,b ] \) will be denoted by \(\mathcal{IR}_{( [ a,b ] )}\).
The following theorem gives a relation between \((IR)\)-integrable and Riemann integrable (R-integrable) (see [33], p. 131):
Theorem 1
Let \(F: [ a,b ] \rightarrow \mathbb{R} _{\mathcal{I}}\)be an interval-valued function such that \(F(t)= [ \underline{F}(t), \overline{F}(t) ]\). \(F\in \mathcal{IR}_{( [ a,b ] )}\)if and only if \(\underline{F}(t)\), \(\overline{F}(t)\in \mathcal{R}_{( [ a,b ] )}\)and
where \(\mathcal{R}_{( [ a,b ] )}\)denotes the all R-integrable functions.
It is seen easily that, if \(F(t)\subseteq G(t)\) for all \(t\in {}[ a,b]\), then
In [1, 34], Zhao et al. introduced a kind of convex interval-valued function as follows.
Definition 2
Let \(h:[c,d]\rightarrow \mathbb{R} \) be a non-negative function, \((0,1)\subseteq {}[ c,d]\) and \(h\neq 0\). We say that \(F:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\) is a h-convex interval-valued function, if for all \(x,y\in {}[ a,b]\) and \(t\in (0,1)\), we have
With \(\operatorname{SX}(h,[a,b],\mathbb{R} _{\mathcal{I}}^{+})\) will show the set of all h-convex interval-valued functions.
The usual notion of convex interval-valued function corresponds to relation (2.1) with \(h(t)=t\), see [23]. Also, if we take \(h(t)=t^{s}\) in (2.1), then Definition 2 gives the other convex interval-valued function defined by Breckner; see [35].
Otherwise, Zhao et al. obtained the following Hermite–Hadamard inequality for interval-valued functions by using h-convexity.
Theorem 2
([1])
Let \(F:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)be an interval-valued function such that \(F(t)=[\underline{F}(t),\overline{F}(t)]\)and \(F\in \mathcal{IR}_{( [ a,b ] )}\), \(h:[0,1]\rightarrow \mathbb{R} \)be a non-negative function and \(h ( \frac{1}{2} ) \neq 0\). If \(F\in \operatorname{SX}(h,[a,b],\mathbb{R} _{\mathcal{I}}^{+})\), then
Remark 1
(i) If \(h(t)=t\), then (2.2) reduces to the following result:
which is obtained by Sadowska in [23].
(ii) If \(h(t)=t^{s}\), then (2.2) reduces to the following result:
which is obtained by Osuna-Gomez et al. in [36].
Theorem 3
Let \(F,G:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)be two interval-valued functions such that \(F(t)=[\underline{F}(t),\overline{F}(t)]\)and \(G(t)=[\underline{G}(t),\overline{G}(t)]\), where \(F,G\in \mathcal{IR}_{( [ a,b ] )}\), \(h_{1},h_{2}:[0,1]\rightarrow \mathbb{R} \)are two non-negative functions and \(h_{1} ( \frac{1}{2} ) h_{2} ( \frac{1}{2} ) \neq 0\). If \(F,G\in \operatorname{SX}(h,[a,b],\mathbb{R} _{\mathcal{I}}^{+})\), then
and
where
Remark 2
If \(h(t)=t\), then (2.5) reduces to the following result:
Remark 3
If \(h(t)=t\), then (2.4) reduces to the following result:
In [2], Budak et al. obtained the following inequalities of Hermite–Hadamard type for the convex interval-valued functions.
Theorem 4
If \(F:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)is a convex interval-valued function such that \(F(t)= [ \underline{F}(t),\overline{F}(t) ] \)and \(\alpha >0\), then we have
Theorem 5
If \(F,G:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)are two convex interval-valued functions such that \(F(t)= [ \underline{F}(t),\overline{F}(t) ] \)and \(G(t)= [ \underline{G}(t),\overline{G}(t) ] \), then for \(\alpha >0\)we have
and
where \(M(a,b)\)and \(N(a,b)\)are defined in Theorem 3.
For the other fractional inequalities for the convex interval-valued functions, see [37].
3 Interval-valued approximately convexities
In this section we define a new class of interval-valued approximately h-convex functions, which is depending upon a given function. We discuss some special cases of our new definition and find new definitions of approximately h-convex functions. We let \((X, \Vert \cdot \Vert _{I})\) be a normed quasilinear space, let I be a nonempty interval-valued convex subset of X, \(H:X\times X\rightarrow \mathbb{R} \) and let \(h:(0,1)\rightarrow \mathbb{R} \) be the given functions.
Definition 3
A function \(F:I\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\) is said to be interval-valued approximately h-convex function, if
for all \(t\in (0,1)\) and \(a,b\in I\).
Now we discuss some special cases of Definition 3.
-
I.
If we use \(H(x,y)=\epsilon ( \Vert x-y \Vert )^{\gamma }\) for some \(\epsilon \in \mathbb{R} \) and \(\gamma >1\) in Definition 3, then we have a new definition of an interval-valued approximately convex function which is called an interval-valued γ-approximately h-convex function.
Definition 4
A function \(F:I\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\) is said to be an interval-valued γ-approximately h-convex function, if
for all \(t\in (0,1)\) and \(a,b\in I\).
-
II.
If we use \(H(x,y)=\epsilon ( \Vert x-y \Vert )\) for some \(\epsilon \in \mathbb{R} \) in Definition 3, then we have a new definition of an interval-valued approximately convex function which is called an interval-valued ϵ-approximately h-convex function.
Definition 5
A function \(F:I\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\) is said to be an interval-valued ϵ-approximately h-convex function, if
for all \(t\in (0,1)\) and \(a,b\in I\).
-
III.
If we use \(H(x,y)=-\mu t(1-t) \Vert y-x \Vert ^{2}\) for some \(\mu >0\) in Definition 3, then we have a new definition of an interval-valued approximately convex function which is called an interval-valued strongly h-convex function.
Definition 6
A function \(F:I\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\) is said to be an interval-valued strongly h-convex function, if
for all \(t\in (0,1)\) and \(a,b\in I\).
-
IV.
If we use \(H(x,y)=\mu t(1-t) \Vert y-x \Vert ^{2}\) for some \(\mu >0\) in Definition 3, then we have a new definition of interval-valued approximately convex function which is called an interval-valued relaxed h-convex function.
Definition 7
A function \(F:I\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\) is said to be an interval-valued relaxed h-convex function, if
for all \(t\in (0,1)\) and \(a,b\in I\).
4 Interval-valued generalized fractional integral operators
In this section, we define a generalized fractional integral operator for the interval-valued functions and discuss special cases of our newly define integral operator.
Let us define a function \(\mathfrak{\varphi }:[0,+\infty )\rightarrow {}[ 0,+\infty )\) satisfying the following conditions:
where \(A_{1},A_{2},A_{3}>0\) are independent of \(r,s>0\). If \(\mathfrak{\varphi }(r)r^{\alpha }\) is increasing for some \(\alpha \geq 0\) and \(\frac{\mathfrak{\varphi }(r)}{r^{\beta }}\) is decreasing for some \(\beta \geq 0\), then φ satisfies (4.1)–(4.4); see [12]. Meanwhile, in [11], Sarikaya and Ertuğral defined the following generalized fractional integrals:
Therefore, we can give the following new definitions.
Definition 8
Let \(F:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}\) be an interval-valued function such that \(F(t)= [ \underline{F}(t),\overline{F}(t) ] \) and \(F\in \mathcal{IR}_{( [ a,b ] )}\). Then the interval-valued left-sided and right-sided generalized fractional integrals of the function F, respectively, are given as
Corollary 1
Let \(F:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}\)be an interval-valued function such that \(F(t)= [ \underline{F}(t),\overline{F}(t) ] \)and \(F\in \mathcal{IR}_{( [ a,b ] )}\). Then, we have
and
The most important feature of interval-valued generalized fractional integrals is that they generalize some types of fractional integrals such as the Riemann–Liouville fractional integral, the k-Riemann–Liouville fractional integral, Katugampola fractional integrals, the conformable fractional integral, and Hadamard fractional integrals. These important special cases of the integral operators (4.5) and (4.6) are mentioned below.
i) Taking \(\mathfrak{\varphi } ( t ) =t\), the operators (4.5) and (4.6) reduce to the interval-valued Riemann integrals as follows:
ii) Taking \(\mathfrak{\varphi } ( t ) = \frac{t^{\alpha }}{\Gamma ( \alpha ) }\), the operators (4.5) and (4.6) reduce to the interval-valued Riemann–Liouville fractional integrals as follows:
iii) Taking \(\mathfrak{\varphi } ( t ) = \frac{t^{\frac{\alpha }{k}}}{k\Gamma _{k} ( \alpha ) }\), the operators (4.5) and (4.6) reduce to the interval-valued k-Riemann–Liouville fractional integrals as follows:
where
and
iv) Taking \(\mathfrak{\varphi } ( t ) =t ( x-t ) ^{\alpha -1}\), the operator (4.5) reduces to the interval-valued conformable fractional operator as follows:
5 Main results
In this section, we prove some inequalities of Hermite–Hadamard type for the interval-valued approximately h-convex functions via generalized fractional integrals. We use for brevity the following notations in the next new results:
and
Theorem 6
If \(F:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)is an interval-valued approximately h-convex function such that \(F(t)= [ \underline{F}(t),\overline{F}(t) ] \), then we have the following inequalities for the generalized fractional integrals:
Proof
Since F is interval-valued approximately h-convex function, we have
By setting \(x=ta+(1-t)b\) and \(y=tb+(1-t)a\) in (5.2), we obtain
Multiplying both sides of (5.3) by \(\frac{\mathfrak{\varphi }((b-a)t)}{t}\) and integrating the resultant one with respect to t over \([0,1]\), we get
In Eq. (5.4), using Theorem 1, we obtain
Similarly, we have
Hence, we achieved our first inequality. To prove the second inequality since F is interval-valued approximately h-convex function, we get
and
Adding (5.5) and (5.6), we have
Multiplying (5.7) by \(\frac{\mathfrak{\varphi }((b-a)t)}{t}\) on both sides and integrating the resultant one with respect to t over \([0,1]\), we have
This completes the proof. □
Corollary 2
If we choose \(\mathfrak{\varphi }(t)=t\)in Theorem 6, then we have the following inequalities:
Corollary 3
If we choose \(\mathfrak{\varphi }(t)=\frac{t^{\alpha }}{\Gamma (\alpha )}\)in Theorem 6, then we have the following inequalities for the Riemann–Liouville fractional integrals:
Theorem 7
If \(F,G:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)are two interval-valued approximately h-convex functions such that \(F(t)= [ \underline{F}(t),\overline{F}(t) ] \)and \(G(t)= [ \underline{G}(t),\overline{G}(t) ] \), then we have the following inequality for the generalized fractional integrals:
where \(M(a,b)\)and \(N(a,b)\)are defined in Theorem 3and
Proof
Since F and G are interval-valued approximately h-convex functions for \(t\in {}[ 0,1]\), we have
and
Multiplying (5.12) and (5.13), we get
Similarly, we obtain
Adding (5.14) and (5.15), we have the following relation:
Multiplying (5.16) by \(\frac{\mathfrak{\varphi }((b-a)t)}{t}\) on both sides and integrating the resultant one with respect to t over \({}[ 0,1]\), we get
Using Theorem 1 in Eq. (5.17), we have
and
Substituting (5.18) and (5.19) in Eq. (5.17), we have our desired result (5.11). This completes the proof. □
Corollary 4
Under the assumptions of Theorem 7with \(\mathfrak{\varphi }(t)=t\), then we have the following inequality:
Corollary 5
If we use \(\mathfrak{\varphi }(t)=\frac{t^{\alpha }}{\Gamma (\alpha )}\)in Theorem 7, then we have the following inequality for the Riemann–Liouville fractional integrals:
Theorem 8
If \(F,G:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)are two interval-valued approximately h-convex functions such that \(F(t)= [ \underline{F}(t),\overline{F}(t) ] \)and \(G(t)= [ \underline{G}(t),\overline{G}(t) ] \), then we have the following inequality for the generalized fractional integrals:
where \(M(a,b)\), \(N(a,b)\)and \(K_{1}\), \(K_{2}\), \(K_{3}\), \(P(a,b)\)are defined from Theorem 3and Theorem 7, respectively.
Proof
For \(t\in {}[ 0,1]\), we can write
Since F and G are two interval-valued approximately h-convex functions, we have
Multiplying by \(\frac{\mathfrak{\varphi }((b-a)t)}{t}\) both sides of inequality (5.23) and integrating the resultant one with respect to t over \([0,1]\), we obtain
By changing the variable of integration we achieved the desired inequality (5.22). □
Corollary 6
Under the assumptions of Theorem 8with \(\mathfrak{\varphi }(t)=t\), then we have the following inequality:
Corollary 7
Under the assumptions of Theorem 8with \(\mathfrak{\varphi }(t)=\frac{t^{\alpha }}{\Gamma (\alpha )}\), then we have the following inequality for the Riemann–Liouville fractional integrals:
Theorem 9
If \(F:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)is an interval-valued approximately h-convex function such that \(F(t)= [ \underline{F}(t),\overline{F}(t) ] \), then we have the following inequalities for the generalized fractional integrals:
Proof
Since F is interval-valued approximately h-convex function on \([a,b]\), we have
For \(x=\frac{t}{2}a+\frac{2-t}{2}b\) and \(y=\frac{2-t}{2}a+\frac{t}{2}b\), we get
Multiplying by \(\frac{\varphi ( \frac{(b-a)}{2}t ) }{t}\) both sides of inequality (5.27) and integrating the resultant one with respect to t over \([0,1]\), we obtain
Using Theorem 1 and Eq. (5.28), we have
Similarly, we get
Hence, we proved the first inequality. To prove the second inequality of (5.26), first we note that, since F is an interval-valued approximately h-convex function, we have
and
Adding (5.29) and (5.30), we get
Multiplying by \(\frac{\varphi ( \frac{(b-a)}{2}t ) }{t}\) both sides of inequality (5.31) and integrating the resultant one with respect to t over \([0,1]\), we obtain
By changing the variables of integration we have the second inequality of (5.26). □
Corollary 8
If we choose \(\mathfrak{\varphi }(t)=t\)in Theorem 9, then we have the following inequalities:
Corollary 9
Taking \(\mathfrak{\varphi } ( t ) = \frac{t^{\alpha }}{\Gamma (\alpha )}\)in Theorem 9, then we have the following inequalities for the interval-valued fractional operators:
Theorem 10
If \(F,G:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)are two interval-valued approximately h-convex functions such that \(F(t)= [ \underline{F}(t),\overline{F}(t) ] \)and \(G(t)= [ \underline{G}(t),\overline{G}(t) ] \), then we have the following inequality for the generalized fractional integrals:
where \(M(a,b)\)and \(N(a,b)\)are defined in Theorem 3and
Proof
Since F and G are two interval-valued approximately h-convex functions,
and
Multiplying (5.35) and (5.36), we have
Similarly, we get
Adding (5.37) and (5.38), we obtain the following relation:
Multiplying by \(\frac{\varphi ( \frac{(b-a)}{2}t ) }{t}\) both sides of inequality (5.39) and integrating the resultant one with respect to t over \([0,1]\), we have
By using Theorem 1 in Eq. (5.40), we obtain our required inequality. □
Corollary 10
Taking \(\mathfrak{\varphi } ( t ) =t\)in Theorem 10, then we have the following inequality:
Corollary 11
Taking \(\mathfrak{\varphi } ( t ) = \frac{t^{\alpha }}{\Gamma (\alpha )}\)in Theorem 10, then we have the following inequality for the interval-valued fractional operators:
Theorem 11
If \(F,G:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)are two interval-valued approximately h-convex functions such that \(F(t)= [ \underline{F}(t),\overline{F}(t) ] \)and \(G(t)= [ \underline{G}(t),\overline{G}(t) ] \), then we have the following inequality for the generalized fractional integrals:
where \(M(a,b)\), \(N(a,b)\)and \(K_{4}\), \(K_{5}\), \(K_{6}\)are defined in Theorem 3and Theorem 10, respectively.
Proof
Since F and G are two interval-valued approximately h-convex functions on \([a,b]\), we have
For \(x=\frac{2-t}{2}a+\frac{t}{2}b\) and \(y=\frac{t}{2}a+\frac{2-t}{2}b\), we obtain
Similarly, we get
Multiplying the inequalities (5.45) and (5.46), we obtain
Multiplying by \(\frac{\varphi ( \frac{(b-a)}{2}t ) }{t}\) both sides of inequality (5.47) and integrating the resultant one with respect to t over \([0,1]\), we obtain our result (5.43). □
Corollary 12
Taking \(\mathfrak{\varphi } ( t ) =t\)in Theorem 11, then we have the following inequality:
Corollary 13
Taking \(\mathfrak{\varphi } ( t ) = \frac{t^{\alpha }}{\Gamma (\alpha )}\)in Theorem 11, then we have the following inequality for the interval-valued fractional operators:
Theorem 12
If \(F:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)is interval-valued approximately h-convex function such that \(F(t)= [ \underline{F}(t),\overline{F}(t) ] \), then we have the following inequalities for the generalized fractional integrals:
Proof
Since F is an interval-valued approximately h-convex function on \([a,b]\), we have
For \(x=\frac{1-t}{2}a+\frac{1+t}{2}b\) and \(y=\frac{1+t}{2}a+\frac{1-t}{2}b\), we get
Multiplying by \(\frac{\varphi ( \frac{(b-a)}{2}t ) }{t}\) both sides of inequality (5.51) and integrating the resultant one with respect to t over \([0,1]\), we obtain
By using Theorem 1 in Eq. (5.52), we have
Similarly, we get
Hence, we proved the first inequality. To prove the second inequality of (5.50), first we note that, since F is an interval-valued approximately h-convex function, we have
and
Adding (5.53) and (5.54), we have
Multiplying by \(\frac{\varphi ( \frac{(b-a)}{2}t ) }{t}\) both sides of inequality (5.55) and integrating the resultant one with respect to t over \([0,1]\), we obtain
This completes the proof. □
Corollary 14
If we choose \(\mathfrak{\varphi }(t)=t\)in Theorem 12, then we have the following inequalities:
Corollary 15
Taking \(\mathfrak{\varphi } ( t ) = \frac{t^{\alpha }}{\Gamma (\alpha )}\)in Theorem 12, then we have the following inequalities for the interval-valued fractional operators:
Theorem 13
If \(F,G:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)are two interval-valued approximately h-convex functions such that \(F(t)= [ \underline{F}(t),\overline{F}(t) ] \)and \(G(t)= [ \underline{G}(t),\overline{G}(t) ] \), then we have the following inequality for the generalized fractional integrals:
where \(M(a,b)\)and \(N(a,b)\)are defined in Theorem 3and
Proof
Since F and G are two interval-valued approximately h-convex functions,
and
Multiplying (5.59) and (5.60), we have
Similarly, we get
Adding (5.61) and (5.62), we obtain the following relation:
Multiplying by \(\frac{\varphi ( \frac{(b-a)}{2}t ) }{t}\) both sides of inequality (5.63) and integrating the resultant one with respect to t over \([0,1]\), we have
By using Theorem 1 in Eq. (5.64), we obtain our required inequality. □
Corollary 16
If we choose \(\mathfrak{\varphi }(t)=t\)in Theorem 13, then we get the following inequality:
Corollary 17
Taking \(\mathfrak{\varphi } ( t ) = \frac{t^{\alpha }}{\Gamma (\alpha )}\)in Theorem 13, then we have the following inequality for the interval-valued fractional operators:
Theorem 14
If \(F,G:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)are two interval-valued approximately h-convex functions such that \(F(t)= [ \underline{F}(t),\overline{F}(t) ] \)and \(G(t)= [ \underline{G}(t),\overline{G}(t) ] \), then we have the following inequality for the generalized fractional integrals:
where \(M(a,b)\), \(N(a,b)\)and \(K_{7}\), \(K_{8}\), \(K_{9}\)are defined in Theorem 3and Theorem 13, respectively.
Proof
Since F and G are two interval-valued approximately h-convex functions on \([a,b]\), we have
For \(x=\frac{1-t}{2}a+\frac{1+t}{2}b\) and \(y=\frac{1+t}{2}a+\frac{1-t}{2}b\), we obtain
Similarly, we get
Multiplying the inequalities (5.69) and (5.70), we obtain
Multiplying by \(\frac{\varphi ( \frac{(b-a)}{2}t ) }{t}\) both sides of inequality (5.71) and integrating the resultant one with respect to t over \([0,1]\), we obtain our result (5.67). □
Corollary 18
Taking \(\mathfrak{\varphi } ( t ) =t\)in Theorem 14, then we have the following inequality:
Corollary 19
Taking \(\mathfrak{\varphi } ( t ) = \frac{t^{\alpha }}{\Gamma (\alpha )}\)in Theorem 14, then we have the following inequality for the interval-valued fractional operators:
6 Some special cases
In this section, we discuss some special cases from our main results.
From Theorem 6, we have the following result.
Corollary 20
If \(F:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)is interval-valued γ-approximately h-convex function, then
Corollary 21
If \(F,G:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)are two interval-valued γ-approximately h-convex functions, then
Corollary 22
If \(F,G:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)are two interval-valued ϵ-approximately h-convex functions, then
From Theorem 8, we obtain the following result.
Corollary 23
If \(F,G:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)are two interval-valued γ-approximately h-convex functions, then
Corollary 24
If \(F,G:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)are two interval-valued ϵ-approximately h-convex functions, then
From Theorem 9, we have the following result.
Corollary 25
If \(F:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)is interval-valued γ-approximately h-convex function, then
Corollary 26
If \(F:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)is interval-valued ϵ-approximately h-convex function, then
From Theorem 10, we get
Corollary 27
If \(F,G:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)are two interval-valued γ-approximately h-convex functions, then
Corollary 28
If \(F,G:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)are two interval-valued ϵ-approximately h-convex functions, then
From Theorem 11, we obtain the following result.
Corollary 29
If \(F,G:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)are two interval-valued γ-approximately h-convex functions, then
Corollary 30
If \(F,G:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)are two interval-valued ϵ-approximately h-convex functions, then
From Theorem 12, we have the following result.
Corollary 31
If \(F:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)is interval-valued γ-approximately h-convex function, then
Corollary 32
If \(F:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)is interval-valued ϵ-approximately h-convex function, then
From Theorem 13, we get the following result.
Corollary 33
If \(F,G:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)are two interval-valued γ-approximately h-convex functions, then
Corollary 34
If \(F,G:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)are two interval-valued ϵ-approximately h-convex functions, then
From Theorem 14, we obtain the following result.
Corollary 35
If \(F,G:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)are two interval-valued γ-approximately h-convex functions, then
Corollary 36
If \(F,G:[a,b]\rightarrow \mathbb{R} _{\mathcal{I}}^{+}\)are two interval-valued ϵ-approximately h-convex functions, then
Remark 4
Applying our Theorems 6–14, where \(H(x,y)=-\mu t(1-t) \Vert y-x \Vert ^{2}\) and \(H(x,y)=\mu t(1-t) \Vert \frac{1}{y}-\frac{1}{x} \Vert ^{2}\) for some \(\mu >0\), then we can obtain some new inequalities for interval-valued strongly and relaxed h-convex functions via generalized fractional integrals.
Remark 5
Under the assumptions of Corollaries 2, 4, 6, if we take case V of Definition 3 then we have the results of Zhao et al. [1].
Remark 6
Under the assumptions of Corollaries 3, 5, 7, if we use case V of Definition 3 and \(h(t)=t\), then we have the results of Budak et al. [2].
Remark 7
By using our Theorems 6–14, for suitable options of the function \(\varphi (t)=\frac{t^{\frac{\alpha }{k}}}{k\Gamma _{k}(\alpha )}\); \(\varphi (t)=t(x-t)^{\alpha -1}\) for \(\alpha \in (0,1)\); \(\varphi (t)=\frac{t}{\alpha }\exp (-At)\), where \(A=\frac{1-\alpha }{\alpha }\) for \(\alpha \in (0,1)\), etc., we can construct some new inequalities for interval-valued approximately h-convex functions. Finally, for appropriate choices of the function \(h(t)=1\); \(h(t)=t\); \(h(t)=t^{s}\); \(h(t)=t^{-s}\); \(h(t)=t(1-t)\); \(h(t)= \frac{\sqrt{t}}{2\sqrt{1-t}}\) etc., we can deduce some new interesting inequalities via generalized fractional integrals. We omit their proofs and the details are left to the interested reader.
7 Conclusion
This new class of functions called interval-valued approximately h-convex can be applied to obtain several new results in convex analysis, related optimization theory. The authors hope that this work may stimulate further research in different areas of pure and applied sciences.
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The authors would like to express their sincere gratitude to the editor and the anonymous reviewers for their helpful comments and suggestions.
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This work was supported in part by Special Soft Science Research Projects of Technological Innovation in Hubei Province (2019ADC146), the Fundamental Research Funds for Central Universities (2019B44914), Key Projects of Educational Commission of Hubei Province of China (D20192501), the Natural Science Foundation of Jiangsu Province (BK20180500), the National Key Research and Development Program of China (2018YFC1508100), and this project is partially supported by the National Natural Science Foundation of China (11971241).
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Zhao, D., Ali, M.A., Kashuri, A. et al. Hermite–Hadamard-type inequalities for the interval-valued approximately h-convex functions via generalized fractional integrals. J Inequal Appl 2020, 222 (2020). https://doi.org/10.1186/s13660-020-02488-5
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DOI: https://doi.org/10.1186/s13660-020-02488-5
Keywords
- Hermite–Hadamard-type inequalities
- Interval-valued functions
- Fractional integrals