Abstract
The motivation of this paper is to explore some new inequalities of Steffensen-type which were demonstrated by Pečarić and Kalamir in 2014. The main idea is to investigate a class of certain inequalities by employing diamond- dynamic integral on time scales. In addition, to obtain some new inequalities as special cases, we also extend our results to continuous and discrete calculations.
1. Introduction
In 2014, Pečarić and Kalamir in [1] have established the following interesting theorem:
Theorem 1.
Let be a positive integrable function, be an integrable function, and let . Further, assume that is integrable function such that for all . Moreover, let be the solution of the equation
and be the solution of the equation
If there exists a constant A such that is nonincreasing on and nondecreasing on , and
then
In 1988, Stefan Hilger [2] initiated the theory of time scales in their PhD thesis [3] in order to unify discrete and continuous analysis. The book by Bohner and Peterson [4] on the subject of time scales briefs and organizes much of time scales calculus.
A time scale is an arbitrary nonempty closed subset of the set of real numbers . Throughout the article, we assume that has the topology that it inherits from the standard topology on . We define the forward jump operator for any by
and the backward jump operator for any by
In the preceding two definitions, we set (i.e., if t is the maximum of , then ) and (i.e., if t is the minimum of , then ), where ∅ denotes the empty set.
A point with is said to be right-scattered if , right-dense if , left-scattered if , and left-dense if . Points that are simultaneously right-dense and left-dense are said to be dense points, whereas points that are simultaneously right-scattered and left-scattered are said to be isolated points.
The forward graininess function is defined for any by .
If is a function, then the function is defined by , that is . Similarly, the function is defined by , that is .
The sets , and are introduced as follows: If has a left–scattered maximum , then , otherwise . If has a right–scattered minimum , then , otherwise . Finally, we have .
The interval in is defined by
We define the open intervals and half-closed intervals similarly.
We will use the following crucial relations between calculus on time scales and either differential calculus on or difference calculus on . Note that:
- (i)
- If , then
- (ii)
- If , then
where and ∇ are the forward and backward difference operators, respectively.
The diamond- dynamic derivative of f at t is defined by
For more details on the diamond- calculus on time scales, we refer the interested reader to [5].
Over the past decade, a great number of dynamic inequalities on time scales has been established by many researchers who were motivated by some applications (see [4,6,7,8,9,10,11]). Some researchers developed various results concerning fractional calculus on time scales to produce related dynamic inequalities (see [12,13,14,15]).
Anderson [16] was the first to extend the Steffensen inequality to a general time scale. In particular, he gave the following result.
Theorem 2.
Suppose that with , and f, are ∇-integrable functions such that f is of one sign and nonincreasing and on . Further, assume that such that . Then
In [17], Özkan and Yildirim established the following results regarding diamond- dynamic Steffensen-type inequalities.
Theorem 3.
Let h be a positive integrable function on and f, g be integrable functions on such that f is nonincreasing and for all . Then
where λ is the solution of the equation
If is nondecreasing, then the reverse inequality in (4) holds.
Theorem 4.
Let h be a positive integrable function on and f, g be integrable functions on such that f is nonincreasing and for all . Then
where λ is the solution of the equation
If is nondecreasing, then the reverse inequality in (5) holds.
Theorem 5.
Let h be a positive integrable function on and be integrable functions on such that f is nonincreasing and for all . Then
where λ is the solution of the equation
Theorem 6.
Let f, g and h be -integrable functions defined on with f nonincreasing. Furthermore, let for all . Then
where λ is given by
In this paper, we extend some generalizations of integral Steffensen’s inequality given in [1] to a general time scale, and establish several new sharpened versions of diamond- dynamic Steffensen’s inequality on time scales. As special cases of our results, we recover the integral inequalities given in these papers. Our results also give some new discrete Steffensen’s inequalities. We obtain the new dynamic Steffensen inequalities using the diamond- integrals on time scales. For , the diamond- integral becomes delta integral and for it becomes nabla integral.
Now, we are ready to state and prove the main results of this paper.
2. Main Results
Let us begin by introducing a class of functions that extends the class of convex functions.
Definition 1.
Let ϕ, be positive functions, be a function, and . We say that belongs to the class (respectively, ) if there exists a constant A such that the function is nonincreasing (respectively, nondecreasing) on and nondecreasing (respectively, nonincreasing) on .
We shall need the following lemmas in the proof of our results.
Lemma 1.
Let h be a positive integrable function on and f, g be integrable functions on such that is nonincreasing and for all . Then
where λ is the solution of the equation
If is nondecreasing, then the reverse inequality in (6) holds.
Proof.
Take and in Theorem 3. □
Lemma 2.
Let h be a positive integrable function on and f, g be integrable functions on such that is nonincreasing and for all . Then
where λ is the solution of the equation
If is nondecreasing, then the reverse inequality in (7) holds.
Proof.
Take and in Theorem 4. □
Lemma 3.
Let h be a positive integrable function on and be integrable functions on such that is nonincreasing and for all . Then
where λ is the solution of the equation
Proof.
Take , and in Theorem 5. □
Lemma 4.
Let h be a positive -integrable function on , and f, g be -integrable functions on , Further, assume that is nonincreasing and for all . Then
where λ is given by
Proof.
Take and in Theorem 6. □
Theorem 7.
Let be a positive -integrable function, let be a -integrable function, and let . Let be a -integrable function such that for all . Let be the solution of the equation
and let be the solution of the equation
If and
then
If and (8) holds, the inequality in (9) is reversed.
Proof.
Let , and let , where A is the constant from Definition 1. Since is nonincreasing, from Lemma 1 we obtain
Since is nondecreasing, from Lemma 2 we obtain
Now, from (10) and (11) we obtain
Hence, if (8) is satisfied, then (9) holds. It is similar for . □
Corollary 1.
Setting in Theorem 7, we obtain the delta version of inequality (9) as follows:
Corollary 2.
Setting in Theorem 7, we obtain the nabla version of inequality (9) as follows:
Corollary 3.
If and in Corollary 1, then, with the help of relations (1), we recapture [1] (Theorem 8).
Corollary 4.
If in Corollary 1, then, with the help of relations (2), inequality (12) becomes
Theorem 8.
Let be a positive -integrable function, let be a -integrable function, and let . Let be a -integrable function such that for all . Let be the solution of the equation
and let be the solution of the equation
If and
then
If and (15) holds, the inequality in (16) is reversed.
Proof.
Let , and let , where A is the constant from Definition 1. is nonincreasing, so from Lemma 1 we obtain
is nondecreasing, so from Lemma 1 we obtain
Hence, from (17) and (18) we obtain
Hence, if is satisfied, then (16) holds.
It is similar for . □
Corollary 5.
Setting in Theorem 8, we obtain the delta version of inequality (16) as follows:
Corollary 6.
Setting in Theorem 8, we obtain the nabla version of inequality (16) as follows:
Corollary 7.
If and in Corollary 5, then, with the help of relations (1), we recapture [1] (Theorem 10).
Corollary 8.
If in Corollary 5, then, with the help of relations (2), inequality (19) becomes
Theorem 9.
Let be a positive -integrable function, let be a -integrable function, and let . Let be a -integrable function such that for all . Let be the solution of the equation
and let be the solution of the equation
If and
then
If and (22) holds, the inequality in (23) is reversed.
Proof.
Take and in Theorem 7. □
Corollary 9.
Setting in Theorem 9, we obtain the delta version of inequality (23) as follows:
Corollary 10.
Setting in Theorem 9, we obtain the nabla version of inequality (23) as follows:
Corollary 11.
If and in Corollary 9, then, with the help of relations (1), we recapture [1] (Theorem 16).
Corollary 12.
If in Corollary 9, then, with the help of relations (2), inequality (24) becomes
Theorem 10.
Let be a positive -integrable function, let be a -integrable function, and let . Let be a -integrable function such that for all . Let be the solution of the equation
and let be the solution of the equation
If and
then
If and (27) holds, the inequality in (28) is reversed.
Proof.
Take and in Theorem 8. □
Corollary 13.
Setting in Theorem 10, we obtain the delta version of inequality (28) as follows:
Corollary 14.
Setting in Theorem 10, we obtain the nabla version of inequality (28) as follows:
Corollary 15.
If and in Corollary 13, then, with the help of relations (1), we recapture [1] (Theorem 17).
Corollary 16.
If in Corollary 13, then, with the help of relations (2), inequality (29) becomes
Theorem 11.
Let be a positive -integrable function, let be a -integrable function, and let . Let be a -integrable function such that for all . Let be the solution of the equation
and let be the solution of the equation
If and
then
If and (32) holds, the inequality in (33) is reversed.
Proof.
Take , and in Theorem 7. □
Corollary 17.
Setting in Theorem 11, we obtain the delta version of inequality (33) as follows:
Corollary 18.
Setting in Theorem 11, we obtain the nabla version of inequality (33) as follows:
Corollary 19.
If and in Corollary 17, then, with the help of relations (1), we recapture [1] (Theorem 18).
Corollary 20.
If in Corollary 17, then, with the help of relations (2), inequality (34) becomes
Theorem 12.
Let be a positive -integrable function, let be a -integrable function, and let . Let be a -integrable function such that for all . Let be the solution of the equation
and let be the solution of the equation
If and
then
If and (37) holds, the inequality in (38) is reversed.
Proof.
Take , and in Theorem 8. □
Corollary 21.
Setting in Theorem 12, we obtain the delta version of inequality (38) as follows:
Corollary 22.
Setting in Theorem 12, we obtain the nabla version of inequality (38) as follows:
Corollary 23.
If and in Corollary 21, then, with the help of relations (1), we recapture [1] (Theorem 19).
Corollary 24.
If in Corollary 21, then, with the help of relations (2), inequality (39) becomes
Theorem 13.
Let be a positive -integrable function, let be a -integrable function, and let . Let be a -integrable function such that for all . Let be the solution of the equation
and let be the solution of the equation
If and
then
If and (42) holds, the inequality in (43) is reversed.
Proof.
The proof is similar to that of Theorem 7 applying Lemma 4 for nonincreasing and for nondecreasing. □
Corollary 25.
Setting in Theorem 13, we obtain the delta version of inequality (43) as follows:
Corollary 26.
Setting in Theorem 13, we obtain the nabla version of inequality (43) as follows:
Corollary 27.
If and in Corollary 25, then, with the help of relations (1), we recapture [1] (Theorem 21).
Corollary 28.
If in Corollary 25, then, with the help of relations (2), inequality (44) becomes
Theorem 14.
Let be a positive -integrable function, let be a -integrable function, and let . Let be a -integrable function such that for all . Let be the solution of the equation
and let be the solution of the equation
If and
then
If and (47) holds, the inequality in (48) is reversed.
Proof.
The proof is similar to that of Theorem 8 applying Lemma 4 for nonincreasing and for nondecreasing. □
Corollary 29.
Setting in Theorem 14, we obtain the delta version of inequality (48) as follows:
Corollary 30.
Setting in Theorem 14, we obtain the nabla version of inequality (48) as follows:
Corollary 31.
If and in Corollary 29, then, with the help of relations (1), we recapture [1] (Theorem 22).
Corollary 32.
If in Corollary 29, then, with the help of relations (2), inequality (49) becomes
Theorem 15.
Let be a positive -integrable function, let be a -integrable function, and let . Let be a -integrable function such that for all . Let be the solution of the equation
and let be the solution of the equation
If and
then
If and (52) holds, the inequality in (53) is reversed.
Proof.
The proof is similar to that of Theorem 7 applying Lemma 3 for nonincreasing and Lemma 3 for nondecreasing. □
Corollary 33.
Setting in Theorem 15, we obtain the delta version of inequality (53) as follows:
Corollary 34.
Setting in Theorem 15, we obtain the nabla version of inequality (53) as follows:
Corollary 35.
If and in Corollary 33, then, with the help of relations (1), we recapture [1] (Theorem 23).
Corollary 36.
If in Corollary 33, then, with the help of relations (2), inequality (54) becomes
Theorem 16.
Let be a positive -integrable function, let be a -integrable function, and let . Let be a -integrable function such that for all . Let be the solution of the equation
and let be the solution of the equation
If and -4.6cm0cm
then
If and (57) holds, the inequality in (58) is reversed.
Proof.
The proof is similar to that of Theorem 8 applying Lemma 3 for nonincreasing and Lemma 3 for nondecreasing. □
Corollary 37.
Setting in Theorem 16, we obtain the delta version of inequality (58) as follows:
Corollary 38.
Setting in Theorem 16, we obtain the nabla version of inequality (58) as follows:
Corollary 39.
If and in Corollary 37, then, with the help of relations (1), we recapture [1] (Theorem 24).
Corollary 40.
If in Corollary 37, then, with the help of relations (2), inequality (59) becomes
3. Conclusions
In this important work, we have discussed some new dynamic inequalities of the Steffensen-type by using diamond-alpha integral on time scales. We further presented some relevant inequalities as special cases: discrete inequalities and integral inequalities. These results may possibly be used to obtain more generalized results of several previously obtained inequalities by setting and .
Author Contributions
Conceptualization, resources and methodology, A.A.E.-D. and O.B.; investigation, supervision, J.A.; data curation, O.B.; writing—original draft preparation, A.A.E.-D.; writing—review and editing, J.A.; project administration, A.A.E.-D. and O.B. All authors read and agreed to the published version of the manuscript.
Funding
This research received no external funding.
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
Not applicable.
Conflicts of Interest
The authors declare no conflict of interest.
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