1. Introduction
The area of mathematics known as convex analysis is where we explore the characteristics of convex sets and convex functions. These traditional ideas have numerous uses in both the pure and applied sciences. Everyone is aware of, for instance, how convexity is used in mathematical economics, operations research, optimization theory, and the theory of means, among other fields. The traditional notions of convexity have recently been expanded upon and developed in many ways using fresh and original concepts. For instance, Dragomir [
1] proposed the class of coordinated convex functions and expanded the idea of classical convex functions on the coordinates. The concept of harmonically convex functions was first suggested by Iscan [
2], who also noted that this class benefits from several good features shared by convex functions. The class of interval-valued convex functions was introduced by Nikodem [
3], and its characteristics were covered. Interval-valued harmonically convex functions were first described by Zhao et al. in their publication [
4]. Readers who are interested in more information are advised to read the book [
5]. Mohan and Neogy [
6] introduced the well-established class of nonconvex functions which is known as preinvex functions. Moreover, they defined a condition to handle a bi-function that is used in invex sets.
The idea of convexity’s relationship to the theory of inequalities is another endearing feature. Numerous inequalities that are well-known to us are a direct result of using the convexity condition of functions. The Hermite–Hadamard inequality is among one of the findings in this area that have received the most research.
The 𝐻𝐻 inequality [
7,
8] for convex mapping
on an interval
for all
where
is a convex set. If the mapping is concave, then inequality (1) is reversed.
Fejér considered the major generalizations of 𝐻𝐻 inequality in [
9] which is known as 𝐻𝐻–Fejér inequality.
Let
be a convex mapping on a convex set
and
. Then,
If , then we obtain (1) from (2). For concave mapping, the above inequality (2) is reversed. Many inequalities may be found using special symmetric mapping for convex mappings with the help of inequality (2).
With the use of fractional calculus, Sarikaya et al. [
10] were able to derive fractional analogs of the Hermite–Hadamard inequality. See [
11] for some more current research on Hermite–Hadamard’s inequality and its uses.
On the other hand, interval analysis is a crucial component of mathematics and is employed in computer models as one method for addressing interval uncertainty. Although Archimedes’ calculation of a circle’s circumference is where this theory first appeared, significant research on the subject was not published until the 1950s. The first book [
12] on interval analysis was published in 1966 by Moore, the inventor of interval calculus. After that, other academics studied the theory and uses of interval analysis. Integral inequalities resulting from interval-valued functions have recently attracted the attention of numerous authors. The Hermite–Hadamard inequality for set-valued functions, a more extensive kind of interval-valued mapping, was discovered by Sadowska [
13]:
Let
be a convex interval-valued mapping such that
for all
. Then
If is concave interval-valued mapping, then the above double inclusion relation (3) is reversed.
Many publications have focused on generalizing the inclusions (1)–(3). For instance, Budak et al. [
14] used Riemann–Liouville fractional integrals of interval-valued functions to demonstrate the Hermite–Hadamard inclusion. Several works [
15,
16,
17] examined the generalization of (3) using various general convexities. The analogous Hermite–Hadamard inclusions for interval-valued functions with two variables were also demonstrated by numerous writers [
18,
19,
20,
21]. We recommend the following articles [
21,
22,
23,
24] for readers interested.
Khan and his colleagues recently extended the concept of convex interval-valued mappings (convex
I∙V∙Ms) and the fuzzy interval-valued mappings (convex
F-I∙V∙Ms) term of fuzzy interval-valued convex mappings by using fuzzy-order relation such that the convex
F-I∙V∙Ms (apparently new) concept includes (h1, h2)-convex
F-I∙V∙Ms, see [
25] and harmonic convex
F-I∙V∙Ms, see [
26]. To illustrate inequalities of the Hermite–Hadamard, Hermite–Hadamard–Fejér, and Pachpatte types, his team utilized h-preinvex
F-I∙V∙Ms, see [
27], (h1, h2)-preinvex
F-I∙V∙Ms, see [
28], and higher-order preinvex
F-I∙V∙Ms, see [
29], Recently Khan et al. [
30] introduced new versions of Hermite–Hadamard and Hermite–Hadamard–Fejér type inequalities by using the introduced concept of fuzzy Riemann–Liouville fractional integrals via
U∙D F-N∙V∙Ms. For various recent achievements related to the notion of fuzzy interval-valued analysis of some well-known integral inequalities, we refer interested readers to study some basic concepts related to fuzzy calculus, see [
31,
32,
33,
34,
35,
36,
37,
38,
39,
40,
41,
42,
43,
44,
45,
46,
47,
48,
49,
50,
51,
52,
53,
54,
55] and the references therein.
Motivated and inspired by existing research, we have presented a new extension of HH inequalities for the newly introduced class of U∙D -pre-invex F-N∙V∙Ms using fuzzy inclusion relation. With the aid of this class, we have created new versions of the HH inequalities that take advantage of the fuzzy Riemann integral operators. We also looked at the applicability of our findings in exceptional circumstances.
2. Preliminaries
Let
be the space of all closed and bounded intervals of
and
be defined by
If , then is said to be degenerate. In this article, all intervals will be non-degenerate intervals. If , then is called the positive interval. The set of all positive intervals is denoted by and defined as
Let
and
be defined by
Then, the Minkowski difference
, addition
and
for
are defined by
Remark 1. (i) For given
the relation
defined on
by
for all
it is a partial interval inclusion relation. The relation
coincident to
on
It can be easily seen that “
” looks like “up and down” on the real line
so we determine that
is “up and down” (or “
U∙D” order, in short) [
40].
(ii) For each given
we say that
if and only if
or
, it is a partial interval order relation. The relation
coincident to
on
It can be easily seen that
looks like “left and right” on the real line
so we determine that
is “left and right” (or “LR” order, in short) [
39,
40].
For
the Hausdorff–Pompeiu distance between intervals
, and
is defined by
It is familiar fact that
is a complete metric space, see [
33,
37,
38].
Definition 1 ([
32]).
A fuzzy subset of is distinguished by a mapping called the membership mapping of . That is, a fuzzy subset of is a mapping . So for further study, we have chosen this notation. We appoint to denote the set of all fuzzy subsets of .
Let . Then, is known as a fuzzy number or fuzzy number if the following properties are satisfied by :
- (1)
should be normal if there exists and
- (2)
should be upper semi-continuous on if for given there exist there exist such that for all with
- (3)
should be fuzzy convex that is for all and
- (4)
should be compactly supported that is is compact.
We appoint to denote the set of all fuzzy numbers of .
Definition 2 ([
32,
33]).
Given , the level sets or cut sets are given by for all and by . These sets are known as -level sets or -cut sets of .
Proposition 1 ([
34]).
Let . Then relation given on byit is left and right order relation.
Proposition 2 ([
30]).
Let . Then relation given on byit is up and down order relation on .
Proof: The proof follows directly from the up and down relation defined on . □
Remember the approaching notions, which are offered in the literature. If
and
, then, for every
the arithmetic operations are defined by
These operations follow directly from the Equations (5)–(7), respectively.
Theorem 1 ([
33]).
The space dealing with a supremum metric i.e., for is a complete metric space, where denotes the well-known Hausdorff metric on space of intervals.
3. Riemann Integral Operators for the Interval- and Fuzzy-Number Valued Mappings
Now we define and discuss some properties of fractional integral operators of interval- and fuzzy-number valued mappings.
Theorem 2 ([
33,
34]).
If is an interval-valued mapping (I-V∙M) satisfying that , then is Aumann integrable (IA-integrable) over when and only when and both are integrable over such that Definition 3 ([
39]).
Let is called fuzzy-number valued mapping. Then, for every , as well as -levels define the family of I-V∙Ms satisfying that for every Here, for every the endpoint real-valued mappings are called lower and upper mappings of .
Definition 4 ([
39]).
Let be a F-N∙V∙M. Then is said to be continuous at if for every is continuous when and only when, both endpoint mappings , and are continuous at Definition 5 ([
33]).
Let be F-N∙V∙M. The fuzzy Aumann integral (-integral) of over denoted by , is defined level-wise bywhere for every is -integrable over if Theorem 3 ([
34]).
Let be a F-N∙V∙M as well as -levels define the family of I-V∙Ms satisfying that for every and for every Then is -integrable over when, and only when, and both are integrable over . Moreover, if is -integrable over thenfor every Breckner discussed the emerging idea of interval-valued convexity in [
35].
An interval valued mapping
is called convex inteval valued mapping if
for all
, where
is the collection of all real valued intervals. If (20) is reversed, then
is called concave.
Definition 6 ([
31]).
The F-N∙V∙M is called convex F-N∙V∙M on iffor all where for all If (21) is reversed then, is called concave F-N∙V∙M on .
is affine if and only if it is both convex and concave F-N∙V∙M.
Definition 7 ([
40]).
The F-N∙V∙M is called U∙D convex F-N∙V∙M on iffor all where for all If (22) is reversed then, is called U∙D concave F-N∙V∙M on .
is U∙D affine F-N∙V∙M if and only if it is both U∙D convex and U∙D concave F-N∙V∙M.
Definition 8 ([
44]).
Let be an invex set and such that . Then F-N∙V∙M is said to be U∙D -pre-invex on with respect to iffor all where The mapping is said to be U∙D -pre-incave on with respect to if inequality (23) is reversed.
Theorem 4 ([
44]).
Let be an F-N∙V∙M, whose -levels define the family of I-V∙Ms are given byfor all and for all . Then, is U∙D -pre-invex F-N∙V∙M on if and only if, for all is a -pre-invex mapping and is a -pre-incave mapping.
The following assumption is required to prove the next result regarding the bi-function which is known as:
Condition C. See [
6]. Let
be an invex set with respect to
For any
and
,
Clearly, for
= 0, we have
= 0 if, and only if,
, for all
. For the applications of Condition C, see [
6,
27,
28,
29,
41,
44,
45].
4. Up and Down Fuzzy-Number Valued Mappings and Related Fuzzy Integral Inequalities
In this section, we discuss our key findings. We begin by introducing the category of U∙D -pre-invex mappings with fuzzy number values.
Definition 9. Letbe an invex set andsuch that. Then F-N∙V∙Mis said to be U∙D-pre-invex onwith respect toiffor allwhere The mappingis said to be U∙D-pre-incave onwith respect toif inequality (25) is reversed. Remark 2. The U∙D-pre-invex F-N∙V∙Ms have some very nice properties similar to pre-invex F-N∙V∙M,
- (1)
ifis U∙D-pre-invex F-N∙V∙M, thenis also U∙D-pre-invex for.
- (2)
ifandboth are U∙D-pre-invex F-N∙V∙Ms, thenis also U∙D-pre-invex F-N∙V∙M.
Now we discuss some new special cases of U∙D -pre-invex F-N∙V∙Ms:
If
then
U∙D -pre-invex
F-N∙V∙M becomes
U∙D -pre-invex
F-N∙V∙M, that is
If then is called U∙D -convex F-N∙V∙M.
If
then
U∙D h-pre-invex
F-N∙V∙M becomes
U∙D pre-invex
F-N∙V∙M, see [
44].
If
then
is called
U∙D convex
F-N∙V∙M, this is the resulting new one:
If
and
then
is called
U∙D convex
F-N∙V∙M, this is the resulting new one:
If
then
U∙D -pre-invex
F-N∙V∙M becomes
U∙D -pre-invex
F-N∙V∙M, this is the resulting new one:
If then is called -F-N∙V∙M.
Theorem 5. Letbe an invex set and, and letbe a F-N∙V∙M with, whose-levels define the family of I∙V∙Msis given byfor alland for all. Then,is U∙D-pre-invex F-N∙V∙M onif, and only if, for all andare-pre-invex and-pre-incave functions, respectively. Proof. Assume that for each
and
are
-pre-invex and
-pre-incave functions on
, respectively. Then from (25), we have
and
Then by (30), (13), and (15), we obtain
that is
Hence, is U∙D -pre-invex F-N∙V∙M on .
Conversely, let
be an U∙D
-pre-invex
F-N∙V∙M on
Then, for all
and
we have
Therefore, from (13), we have
Again, from (30), (13), and (15), we obtain
for all
and
Then by
U∙D -pre-invexity of
, we have for all
and
such that
and
for each
Hence, the result follows. □
Example 1.
We considerforand the F-N∙V∙Mdefined by,then, for eachwe have. Since are-pre-invex functionsfor each. Henceis U∙D-pre-invex F-N∙V∙M. Now we have obtained some new definitions from the literature which will be helpful to investigate some classical and new results as special cases of the main results.
Definition 10. Letbe a F-N∙V∙M, whose-levels define the family of I-V∙Msare given byfor alland for all. Then,is lower U∙D-pre-invex (-pre-incave) F-N∙V∙M onif, and only if, for alland Definition 11. Letbe a F-N∙V∙M, whose-levels define the family of I-V∙Msare given byfor alland for all
. Then,
is upper U∙D
-pre-invex (-pre-incave) F-N∙V∙M on
if, and only if, for all
and Remark 3. Both concepts “U∙D-pre-invex F-N∙V∙M” and “-pre-invex F-N∙V∙M, see [
28]
” behave alike when is lower U∙D -pre-invex F-N∙V∙M. If we take
, then we acquire classical and new results from Definitions 7–9, Remarks 1 and 2, and Theorem 5, see [
16,
25,
27,
30,
41,
42,
44,
45].
The up and down -pre-invex fuzzy-number valued mappings version of a Hermite–Hadamard type inequality can be represented as follows.
Theorem 6 .
Let be an U∙D -pre-invex F-N∙V∙M with and , whose -levels define the family of I∙V∙Ms are given by for all and for all . If , then If is U∙D-pre-incave F-N∙V∙M, then (37) is reversed such that Proof. Let be an U∙D -pre-invex F-N∙V∙M. Then, by hypothesis, we have
Therefore, for every
, we have
In a similar way as above, we have
Combining (39) and (40), we have
which complete the proof. □
Note that, inequality (14) is known as fuzzy HH inequality for U∙D -pre-invex F-N∙V∙M.
Remark 4. If, then Theorem 7 reduces to the result for U∙D U∙D-pre-invex F-N∙V∙M:
If, then Theorem 6 reduces to the result for U∙D pre-invex F-N∙V∙M, see [
44]
: If, then Theorem 6 reduces to the result for U∙D-pre-invex F-N∙V∙M: Ifis lower U∙D-pre-invex F-N∙V∙M, then we can get the following coming inequality, see [
28]
: If, then Theorem 6 reduces to the result for lower U∙D-pre-invex F-N∙V∙M, see [
28]
: If, then Theorem 6 reduces to the result for lower U∙D pre-invex F-N∙V∙M, see [
28]
: If, then Theorem 6 reduces to the result for lower U∙D-pre-invex F-N∙V∙M, see [
28]
: Ifand, then Theorem 6 reduces to the result for-pre-invex function, see [
41]
: Note that, ifthen integral inequalities (18)–(21) reduce to new ones.
Example 2: We considerfor, and the F-N∙V∙Mdefined by, Then, for each
we have
. Since left and right end point mappings
and
, are pre-invex and pre-incave mappings with
for each
, respectively, then
is U∙D pre-invex F-N∙V∙M with
. We clearly see that
andfor all Similarly, it can be easily shown thatfor allsuch thatthat isfor all Hence,and the Theorem 6 is verified. The product of two up and down -pre-invex fuzzy-number valued mapping versions of a Hermite–Hadamard type inequality can be represented as follows.
Theorem 7. Letbe two U∙Dand-pre-invex F-N∙V∙Ms withandwhose-levels define the family of I∙V∙Msare given byandfor alland for all. If, thenwhere withand Example 3. We considerfor, and the F-N∙V∙Msdefined by, Then, for eachwe haveandSinceandboth are-pre-invex functions, and, andboth are also-pre-invex functions with respect to same, for eachthen,andboth areand-pre-invex F-N∙V∙Ms, respectively. Now we compute the following:for eachthat means Hence, Theorem 7 is verified.
Theorem 8. Letbe two U∙D- and-pre-invex F-N∙V∙Ms withandrespectively, whose-levels define the family of I∙V∙Msare given byandfor alland for all. Ifandand condition C hold for, thenwhere andand Proof. Using condition C, we can write
By hypothesis, for each
we have
Integrating over
we have
from which, we have
that is
this completes the result. □
Example 4. We considerfor, and the F-N∙V∙Msdefined by, for eachwe haveandas in Example 3, andboth are U∙D- and-pre-invex F-N∙V∙Ms with respect to, respectively. Sinceand,then, we havefor eachthat meanshence, Theorem 8 is demonstrated. The HH Fejér inequalities for U∙D 𝘩-pre-invex FNVMs are now provided. The second HH Fejér inequality is first found for both U∙D h-pre-invex FNVM.
Theorem 9. Letbe an U∙D-pre-invex F-N∙V∙M withand, whose-levels define the family of I∙V∙Msare given byfor alland for all. Ifandsymmetric with respect tothen Proof. Let
be an U∙D
-pre-invex F-N∙V∙M. Then, for each
we have
and
After adding (55) and (56), and integrating over
we get
Since
is symmetric, then
From (54) and (55), we have
that is
hence
this completes the proof. □
Next, we construct the first
HH Fejér inequality for the
U∙D 𝘩-pre-invex
F-N∙V∙M, which generalizes the first
HH Fejér inequality for the
U∙D 𝘩-pre-invex function, see [
4].
Theorem 10. Letbe an U∙D-pre-invex F-N∙V∙M withand, whose-levels define the family of I∙V∙Msare given byfor alland for all. Ifandsymmetric with respect toand, and Condition C for, then Proof. Using condition C, we can write
Since
is an
U∙D -pre-invex, then for
we have
By multiplying (57) by
and integrate it by
over
we obtain
From (58) and (59), we have
From which, we have
that is
Then we complete the proof. □
Remark 5. Ifthen inequalities in Theorems 9 and 10 reduces for U∙D pre-invex F-N∙V∙Ms, see [44]. Ifand, then inequalities in Theorems 9 and 10 reduce for U∙D convex F-N∙V∙Ms, see [44]. Ifis lower U∙D-pre-invex F-N∙V∙M, then inequalities in Theorems 9 and 10 reduce for-pre-invex F-N∙V∙Ms, see [28]. Ifandis lower U∙D-pre-invex F-N∙V∙M, then inequalities in Theorems 9 and 10 reduce for pre-invex F-N∙V∙Ms, see [28]. Ifwith, then Theorems 9 and 10 reduce to classical first and second HH Fejér inequality for 𝘩-pre-invex function, see [41]. Ifwithand, then Theorems 9 and 10 reduce to classical first and second HH Fejér inequality for 𝘩-convex function, see [9]. Example 5. We considerforand the F-N∙V∙Mdefined by, Then, for eachwe have. Sinceandare-pre-invex functionsfor each, thenis-pre-invex F-N∙V∙M. Ifthen, we haveand From (62) and (63), we havefor eachHence, Theorem 9 is verified. From (64) and (65), we have Hence, Theorem 10 is verified.