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arXiv:1704.08190v1 [math.CA] 15 Apr 2017 Generalized Convex Functions and Their Applications Adem Kili¸ cman a, 1 and Wedad Saleh b a Institute for Mathematical Research, University Putra Malaysia, Malaysia e-mail : [email protected] b Department of Mathematics, Putra University of Malaysia, Malaysia e-mail : wed 10 [email protected] Abstract : This study focuses on convex functions and their general- ized. Thus, we start this study by giving the definition of convex functions and some of their properties and discussing a simple geometric property. Then we generalize E-convex functions and establish some their properties. Moreover, we give generalized s-convex functions in the second sense and present some new inequalities of generalized Hermite-Hadamard type for the class of functions whose second local fractional derivatives of order α in absolute value at certain powers are generalized s-convex functions in the second sense. At the end, some examples that these inequalities are able to be applied to some special means are showed. 1 Introduction Let M R be an interval. A function ϕ : M R −→ R is called a convex if for any y 1 ,y 2 M and η [0, 1], ϕ(ηy 1 + (1 η)y 2 ) ηϕ(y 1 ) + (1 η)ϕ(y 2 ). (1.1) If the inequality (1.1) is the strict inequality, then ϕ is called a strict convex function. From a geometrical point of view, a function ϕ is convex provided that the line segment connecting any two points of its graph lies on or above the graph. The function ϕ is strictly convex provided that the line segment 1 Corresponding author email: [email protected] ( Adem Kili¸ cman)
Transcript
Page 1: Generalized Convex Functions and Their Applications · The convexity of functions have been widely used in many branches of mathematics, for example in mathematical analysis, function

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Generalized Convex Functions and Their Applications

Adem Kilicmana,1

and Wedad Salehb

a Institute for Mathematical Research, University Putra Malaysia, Malaysia

e-mail : [email protected] Department of Mathematics, Putra University of Malaysia, Malaysia

e-mail : wed 10 [email protected]

Abstract : This study focuses on convex functions and their general-ized. Thus, we start this study by giving the definition of convex functionsand some of their properties and discussing a simple geometric property.Then we generalize E-convex functions and establish some their properties.Moreover, we give generalized s-convex functions in the second sense andpresent some new inequalities of generalized Hermite-Hadamard type forthe class of functions whose second local fractional derivatives of order α inabsolute value at certain powers are generalized s-convex functions in thesecond sense. At the end, some examples that these inequalities are ableto be applied to some special means are showed.

1 Introduction

Let M ⊆ R be an interval. A function ϕ : M ⊆ R −→ R is called aconvex if for any y1, y2 ∈ M and η ∈ [0, 1],

ϕ(ηy1 + (1− η)y2) ≤ ηϕ(y1) + (1− η)ϕ(y2). (1.1)

If the inequality (1.1) is the strict inequality, then ϕ is called a strict convexfunction.

From a geometrical point of view, a function ϕ is convex provided thatthe line segment connecting any two points of its graph lies on or abovethe graph. The function ϕ is strictly convex provided that the line segment

1Corresponding author email: [email protected] ( Adem Kilicman)

Page 2: Generalized Convex Functions and Their Applications · The convexity of functions have been widely used in many branches of mathematics, for example in mathematical analysis, function

connecting any two points of its graph lies above the graph. If −ϕ is con-vex (resp. strictly convex), then ϕ is called concave (resp. strictly concave).

The convexity of functions have been widely used in many branchesof mathematics, for example in mathematical analysis, function theory,functional analysis, optimization theory and so on. For aproduction func-tion x = ϕ(L), concacity of ϕ is expressed economically by saying thatϕ exhibits diminishing returns. While if ϕ is convex, then it exhibits in-creasing returns. Due to its applications and significant importance, theconcept of convexity has been extended and generalized in several direc-tions, see([2, 12, 23].

Recently, the fractal theory has received significantly remarkable atten-tion from scientists and engineers. In the sense of Mandelbrot, a fractalset is the one whose Hausdorff dimension strictly exceeds the topologicaldimension[10, 19]. Many researchers studied the properties of functions onfractal space and constructed many kinds of fractional calculus by using dif-ferent approaches [2, 6, 31]. Particularly, in [27], Yang stated the analysisof local fractional functions on fractal space systematically, which includeslocal fractional calculus and the monotonicity of function.

Throughout this chapter Rα will be denoted a real linear fractal set.

Definition 1.1. [15] A function ϕ : M ⊂ R −→ Rα is called generalized

convex ifϕ(ηy1 + (1− η)y2) ≤ ηαϕ(y1) + (1− η)αϕ(y2) (1.2)

for all y1, y2 ∈ M , η ∈ [0, 1] and α ∈ (0, 1] .

It is called strictly generalized convex if the inequality (1.2) holds strictlywhenever y1 and y2 are distinct points and η ∈ (0, 1). If −ϕ is generalizedconvex (respectively, strictly generalized convex), then ϕ is generalized con-cave (respectively, strictly generalized concave).

In α = 1, we have a convex function ,i.e, (1.1) is obtained.

Let f ∈ a1I(α)a2 be a generalized convex function on [a1, a2] with a1 < a2.

Then,

f

(

a1 + a2

2

)

≤Γ(1 + α)

(a2 − a1)αa1I

(α)a2

f(x) ≤f(a1) + f(a2)

2α. (1.3)

2

Page 3: Generalized Convex Functions and Their Applications · The convexity of functions have been widely used in many branches of mathematics, for example in mathematical analysis, function

is known as generalized Hermite-Hadmard’s inequality [14]. Many autherspaid attention to the study of generalized Hermite-Hadmard’s inequalityand generalized convex function, see [4, 16]. If α = 1 in (1.3), then [8]

f

(

a1 + a2

2

)

≤1

a2 − a1

∫ a2

a1

f(x)dx ≤f(a1) + f(a2)

2, (1.4)

which is known as classical Hermite-Hadamard inequality, for more prop-erties about this inequality we refer the interested readers to [9, 13].

2 Generalized E-convex Functions

In 1999, Youness [30] introduced E-convexity of sets and functions, whichhave some important applications in various branches of mathematicalsciences [1, 20]. However, Yang [26] showed that some results given byYouness [30] seem to be incorrect. Chen [7] extended E-convexity to asemi E-convexity and discussed some of its properties. For more results onE-convex function or semi E-convex function see [3, 11, 17, 18, 25].

Definition 2.1. [30]

(i) A set B ⊆ Rn is called a E-convex iff there exists E : Rn −→ R

n suchthat

ηE(r1) + (1− η)E(r2) ∈ B,∀r1, r2 ∈ B, η ∈ [0, 1].

(ii) A function g : Rn −→ R is called E-convex (ECF) on a set B ⊆ Rn

iff there exists E : Rn −→ Rn and

g(ηE(r1)+(1−η)E(r2) ≤ ηg(E(r1))+(1−η)g(E(r2)),∀r1, r2 ∈ B, η ∈ [0, 1].

The following propositions were proved in [30]:

Proposition 2.2. (i) Suppose that a set B ⊆ Rn is E-convex, then

E(B) ⊆ B.

(ii) Assume that E(B) is convex and E(B) ⊆ B, then B is E-convex.

Definition 2.3. A function g : Rn −→ Rα is called a generalized E-convex

function (gECF) on a set B ⊆ Rn iff there exists a map E : Rn −→ R

n

such that B is an E-convex set and

g(ηE(r1) + (1− η)E(r2)) ≤ ηαg(E(r1)) + (1− η)αg(E(r2)), (2.1)

3

Page 4: Generalized Convex Functions and Their Applications · The convexity of functions have been widely used in many branches of mathematics, for example in mathematical analysis, function

∀r1, r2 ∈ B, η ∈ (0, 1) and α ∈ (0, 1] On the other hand, if

g(ηE(x1) + (1− η)E(x2)) ≥ ηαg(E(x1)) + (1− η)αg(E(x1)),

∀x1, x2 ∈ B, η ∈ (0, 1) and α ∈ (0, 1] , then g is called generalized E-concaveon B. If the inequality sings in the previous two inequality are strict, theng is called generalized strictly E-convex and generalized strictly E-concave,respectively.

Proposition 2.4. (i) Every ECF on a convex set B is gECF , whereE = I.

(ii) If α = 1 in equation (2.1), then g is called ECF on a set B.

(iii) If α = 1 and E = I in equation (2.1), then g is called a convexfunction

The following two examples show that generalized E-convex functionwhich are not necessarily generalized convex.

Example 2.5. Assume that B ⊆ R2 is given as

B ={

(x1, x2) ∈ R2 : µ1(0, 0) + µ2(0, 3) + µ3(2, 1)

}

,

with µi > 0,

3∑

i=1

µi = 1 and define a map E : R2 −→ R2 such as E(x1, x2) =

(0, x2). The function g : R2 −→ Rα defined by

g(x1, x2) =

{

x3α1 ;x2 < 1,

xα1x3α2 ;x2 ≥ 1

The function g is gECF on B, but is not generalized convex.

Remark 2.6. If α −→ 0 in the above example, then g goes to generalizedconvex function.

Example 2.7. Assume that g : R −→ Rα is defined as

g(r) =

{

1α; r > 0,

(−r)α; r ≤ 0

and assume that E : R −→ R is defined as E(r) = −r2. Hence, R is anE-convex set and g is gECF, but is not generalized convex.

4

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Theorem 2.1. Assume that B ⊆ Rn is an E-convex set and g1 : B −→ R

is an ECF. If g2 : U −→ Rα is non-decreasing generalized convex function

such that the rang g1 ⊂ U , then g2og1 is a gECF on B.

Proof. Since g1 is ECF, then

g1(ηE(r1) + (1− η)E(r2)) ≤ ηg1(E(r1)) + (1− η)g1(E(r2)),

∀r1, r2 ∈ B and η ∈ [0, 1]. Also, since g2 is non-decreasing generalizedconvex function, then

g2og1(ηE(r1) + (1− η)E(r2)) ≤ g2 [ηg1(E(r1)) + (1− η)g1(E(r2))]

≤ ηαg2 (g1(E(r1))) + (1− η)αg2 (g1(E(r2)))

= ηαg2og1(E(r1)) + (1− η)αg2og1(E(r2))

which implies that g2og1 is a gECF on B.

Similarly, g2og1 is a strictly gECF if g2 is a strictly non-decreasinggeneralized convex function.

Theorem 2.2. Assume that B ⊆ Rn is an E-convex set, and gi : B −→

Rα, i = 1, 2, ..., l are generalized E-convex function. Then,

g =

l∑

i=1

kαi gi

is a generalized E-convex on B for all kαi ∈ Rα

Proof. Since gi, i = 1, 2, ..., l are gECF, then

gi(ηE(r1) + (1− η)E(r2)) ≤ ηαgi(E(r1)) + (1− η)αgi(E(r2)),

∀r1, r2 ∈ B , η ∈ [0, 1] and α ∈ (0, 1] . Then,

l∑

i=1

kαi gi(ηE(r1) + (1− η)E(r2))

≤ ηαl∑

i=1

kαi gi(E(r1)) + (1− η)αl∑

i=1

kαi gi(E(r2))

= ηαg(E(r1)) + (1− η)αg(E(r2)).

Thus, g is a gECF.

5

Page 6: Generalized Convex Functions and Their Applications · The convexity of functions have been widely used in many branches of mathematics, for example in mathematical analysis, function

Definition 2.8. Assume that B ⊆ Rn is a convex set. A function g : B −→

Rα is called generalized quasi convex if

g(ηr1 + (1− η)r2) ≤ max {g(r1), g(r2)} ,

∀r1, r2 ∈ B and η ∈ [0, 1].

Definition 2.9. Assume that B ⊆ Rn is an E-convex set. A function

g : B −→ Rα is called

(i) Generalized E-quasiconvex function iff

g(ηE(r1) + (1− η)E(r2) ≤ max {g(E(r1)), E(g(r2))} ,

∀r1, r2 ∈ B and η ∈ [0, 1].

(ii) Strictly generalized E-quasiconcave function iff

g(ηE(r1) + (1− η)E(r2) > min {g(E(r1)), E(g(r2))} ,

∀r1, r2 ∈ B and η ∈ [0, 1].

Theorem 2.3. Assume that B ⊆ Rn is an E-convex set, and gi : B −→

Rα, i = 1, 2, ..., l are gECF. Then,

(i) The function g : B −→ Rα which is defined by g(r) = supi∈I gi(r), r ∈

B is a gECF on B.

(ii) If gi, i = 1, 2, ..., l are generalized E-quasiconvex functions on B, thenthe function g is a generalized E-quasiconvex function on B.

Proof. (i) Due to gi, i ∈ I be gECF on B, then

g(ηE(r1) + (1− η)E(r2))

= supi∈I

gi(ηE(r1) + (1− η)E(r2))

≤ ηα supi∈I

gi(E(r1)) + (1− η)α supi∈I

gi(E(r2))

= ηαg(E(r1)) + (1− η)αg(E(r2)).

Hence, g is a gECF on B.

6

Page 7: Generalized Convex Functions and Their Applications · The convexity of functions have been widely used in many branches of mathematics, for example in mathematical analysis, function

(ii) Since gi, i ∈ I are generalized E-quasiconvex functions on B, then

g(ηE(x1) + (1− η)E(x2)) = supi∈I

gi(ηE(x1) + (1− η)E(x2))

≤ supi∈I

max {gi(E(x1)), gi(E(x2))}

= max

{

supi∈I

gi(E(x1)), supi∈I

gi(E(x2))

}

= max {g(E(x1)), g(E(x2))} .

Hence, g is a generalized E-quasiconvex function on B.

ConsideringB ⊆ Rn is a nonempty E-convex set. From Propostion2.2(i),

we get E(B) ⊆ B.Hence, for any g : B −→ Rα, the restriction g : E(B) −→

Rα of g to E(B) defined by

g(x) = g(x),∀x ∈ E(B)

is well defined.

Theorem 2.4. Assume that B ⊆ Rn, and g : B −→ R

α is a generalizedE-quasiconvex function on B. Then, the restriction g : U −→ R

α of g toany nonempty convex subset U of E(B) is a generalized quasiconvex on U .

Proof. Assume that x1, x2 ∈ U ⊆ E(B), then there exist x∗1, x∗2 ∈ B such

that x1 = E(x∗1) and x2 = E(x∗2). Since U is a convex set, we have

ηx1 + (1− η)x2 = ηE(x∗1) + (1− η)E(x∗2) ∈ U,∀η ∈ [0, 1].

Therefore, we have

g(ηx1 + (1− η)x2) = g(ηE(x∗1) + (1− η)E(x∗2))

≤ max {g(E(x∗1)), g(E(x∗2))}

= max {g(x1), g(x2)}

= max {g(x1), g(x2)} .

Theorem 2.5. Assume that B ⊆ Rn is an E-convex set, and E(B) is a

convex set. Then, g : B −→ Rα is a generalized E-quasiconvex on B iff its

restriction g = g|E(B)is a generalized quasiconvex function on E(B).

7

Page 8: Generalized Convex Functions and Their Applications · The convexity of functions have been widely used in many branches of mathematics, for example in mathematical analysis, function

Proof. Due to Theorem2.4, the if condition is true. Conversely, supposethat x1, x2 ∈ B, then E(x1), E(x2) ∈ E(B) and ηE(x1) + (1 − η)E(x2) ∈E(B) ⊆ B,∀η ∈ [0, 1].Since E(B) ⊆ B, then

g(ηE(x1) + (1− η)E(x2)) = g(ηE(x1) + (1− η)E(x2))

≤ max {g(E(x1)), g(E(x2))}

= max {g(E(x1)), g(E(x2))} .

An analogous result to Theorem2.4 for the generalized E-convex case isas follows:

Theorem 2.6. Assume that B ⊆ Rn is an E-convex set, and g : B −→ R

α

is a gECF on B. Then, the restriction g : U −→ Rα of g to any nonempty

convex subset U of E(B) is a gCF.

An analogous result to Theorem2.5 for the generalized E-convex case isas follows:

Theorem 2.7. Assume that B ⊆ Rn is an E-convex set, and E(B) is a

convex set. Then, g : B −→ Rα is a gECF on B iff its restriction g = g|E(B)

is a gCF on E(B).

The lower level set of goE : B −→ Rα is defined as

Lrα(goE) = {x ∈ B : (goE)(x) = g(E(x)) ≤ rα, rα ∈ Rα} .

The lower level set of g : E(B) −→ Rα is defined as

Lrα(g) = {x ∈ E(B) : g(x) = g(x) ≤ rα, rα ∈ Rα} .

Theorem 2.8. Supose that E(B) be a convex set. A function g : B −→ Rα

is a generalized E-quasiconvex iff Lrα(g) of its restriction g : E(B) −→ Rα

is a convex set for each rα ∈ Rα.

Proof. Due to E(B) be a convex set, then for each E(x1), E(x2) ∈ E(B), wehave ηE(x1)+ (1− η)E(x2) ∈ E(B) ⊆ B. Let x1 = E(x1) and x2 = E(x2).

8

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If x1, x2 ∈ Lrα(g), then g(x1) ≤ rα and g(x2) ≤ rα. Thus,

g(ηx1 + (1− η)x2) = g(ηx1 + (1− η)x2)

= g(ηE(x1) + (1− η)E(x2))

≤ max {g(E(x1)), g(E(x2))}

= max {g(x1), g(x2)}

= max {g(x1), g(x2)}

≤ rα.

which show that ηx1 + (1− η)x2 ∈ Lrα(g). Hence, Lrα(g) is a convex set.

Conversely, let Lrα(g) be a convex set for each rα ∈ Rα, i.e., ηx1+(1−

η)x2 ∈ Lrα(g),∀x1, x2 ∈ Lrα(g) and rα = max {g(x1), g(x2)}. Thus,

g(ηE(x1) + (1− η)E(x2)) = g(ηE(x1) + (1− η)E(x2))

= g(ηx1 + (1− η)x2)

≤ rα

= max {g(x1), g(x2)}

= max {g(E(x1)), g(E(x2))} .

Hence, g is a generalized E-quasiconvex.

Theorem 2.9. Let B ⊆ Rn be a nonempty E-convex set and let g1 : B −→

Rα be a generalized E-quasiconvex on B. Suppose that g2 : R

α −→ Rα is a

non-decreasing function. Then, g2og1 is a generalized E-quasiconvex.

Proof. Since g1 : B −→ Rα is generalized E-quasiconvex onB and g2 : R

α −→Rα is a non-decreasing function, then

(g2og1)(ηE(x1) + (1− η)E(x2)) = g2(g1(ηE(x1) + (1− η)E(x2)))

≤ g2(max {g1(E(x1)), g1(E(x2))})

= max {(g2og1)(E(x1)), (g2og1)(E(x2))}

which shows that g2og1 is a generalized E-quasiconvex on B.

9

Page 10: Generalized Convex Functions and Their Applications · The convexity of functions have been widely used in many branches of mathematics, for example in mathematical analysis, function

Theorem 2.10. If the function g is a gECF on B ⊆ Rn, then g is a

generalized E-quasiconvex on B.

Proof. Assume that g is a gECF on B. Then,

g(ηE(r1) + (1− η)E(r2)) ≤ ηαg(E(r1)) + (1− η)αg(E(r2))

≤ ηα max {g(E(r1)), g(E(r2))}

+(1− η)α max {g(E(r1)), g(E(r2))}

= max {g(E(r1)), g(E(r2))} .

3 Eα-epigraph

Definition 3.1. Assume that B ⊆ Rn × R

α and E : Rn −→ Rn, then the

set B is called Eα-convex set iff

(ηE(x1) + (1− η)E(x2), ηαrα1 + (1− η)αrα2 ) ∈ B

∀(x1, rα1 ), (x2, r

α2 ) ∈ B, η ∈ [0, 1] and α ∈ (0, 1] .

Now, the Eα- epigraph of g is given by

epiEα(g) = {(E(x), rα) : x ∈ B, rα ∈ Rα, g(E(x)) ≤ rα} .

A sufficient condition for g to be a gECF is given by the followingtheorem:

Theorem 3.1. Let E : Rn −→ Rn be an idempoted map. Assume that B ⊆

Rn is an E-convex set and epiEα(g) is an Eα-convex set where g : B −→ R

α,then g is a gECF on B.

Proof. Assume that r1, r2 ∈ B and (E(r1), g(E(r1))), (E(r2), g(E(r2))) ∈epiEα(g). Since epiEα(g) is Eα- convex set, we have

(ηE(E(r1)) + (1− η)E(E(r2)), ηαg(E(r1)) + (1− η)αg(E(r2))) ∈ epiEα(g),

then

g(E(ηE(r1)) + (1− η)E(E(r2))) ≤ ηαg(E(r1)) + (1− η)αg(E(r2)).

Due to E : Rn −→ Rn be an idempotent map, then

g(ηE(r1) + (1− η)E(r2)) ≤ ηαg(E(r1)) + (1− η)αg(E(r2)).

Hence, g is a gECF.

10

Page 11: Generalized Convex Functions and Their Applications · The convexity of functions have been widely used in many branches of mathematics, for example in mathematical analysis, function

Theorem 3.2. Assume that {Bi}i∈I is a family of Eα-convex sets. Then,their intersection ∩i∈IBi is an Eα-convex set.

Proof. Considering (x1, rα1 ), (x2, r

α2 ) ∈ ∩i∈IBi, then (x1, r

α1 ), (x2, r

α2 ) ∈ Bi,

∀i ∈ I. By Eα-convexity of Bi,∀i ∈ I, then we have

(ηE(x1) + (1− η)E(x2), ηαrα1 + (1− η)αrα2 ) ∈ Bi,

∀η ∈ [0, 1] and α ∈ (0, 1] . Hence,

(ηE(x1) + (1− η)E(x2), ηαrα1 + (1− η)αrα2 ) ∈ ∩i∈IBi.

The following theorem is a special case of Theorem 2.3(i) whereE : Rn −→Rn is an idempotent map.

Theorem 3.3. Assume that E : Rn −→ Rn is an idempotent map, and

B ⊆ Rn is an E-convex set. Let {gi}i∈I be a family function which have

bounded from above. If epiEα(gi) are Eα-convex sets, then the function g

which defined by g(x) = supi∈I gi(x), x ∈ B is a gECF on B.

Proof. Since

epiEα(gi) = {(E(x), rα) : x ∈ B, rα ∈ Rα, gi(E(x)) ≤ rα, i ∈ I}

are Eα- convex set in B × Rα, then

∩i∈IepiEα(gi) = {(E(x), rα) : x ∈ B, rα ∈ Rα, gi(E(x)) ≤ rα, i ∈ I}

= {(E(x), rα) : x ∈ B, rα ∈ Rα, g(E(x)) ≤ rα} , (3.1)

where g(E(x)) = supi∈I gi(E(x)), also is Eα-convex set. Hence, ∩i∈IepiEα(gi)is an Eα-epigraph, then by Theorem3.2, g is a generalized E-convex func-tion on B.

4 Generalized s-convex functions

There are many researchers studied the properties of functions on fractalspace and constructed many kinds of fractional calculus by using differentapproaches see [5, 24, 28]

In [14], two kinds of generlized s-convex functions on fractal sets areintroduced as follows:

11

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Definition 4.1. (i) A function ϕ : R+ −→ Rα, is called a generalized

s-convex (0 < s < 1)in the first sense if

ϕ(η1y1 + η2y2) ≤ ηsα1 ϕ(y1) + ηsα2 ϕ(y2) (4.1)

for all y1, y2 ∈ R+ and all η1, η2 ≥ 0 with ηs1 + ηs2 = 1, this class offunctions is denoted by GK1

s .

(ii) A function ϕ : R+ −→ Rα, is called a generalized s-convex (0 <

s < 1) in the second sense if (4.1) holds for all y1, y2 ∈ R+ and allη1, η2 ≥ 0 with η1+η2 = 1, this class of functions is denoted by GK2

s .

In the same paper,[14], Mo and Sui proved that all functions which aregeneralized s-convex in the second sense, for s ∈ (0, 1), are non-negative.

If α = 1 in Definition 4.1 , then we have the classical s-convex functionsin the first sense (second sense) see [8].

Also, in [8], Dragomir and Fitzatrick demonstrated a variation of Hadamard’sinequality which holds for s-convex functions in the second sense.

Theorem 4.2. Assume that ϕ : R+ −→ R+ is a s-convex function in thesecond sense, 0 < s < 1 and y1, y2 ∈ R+, y1 < y2. If ϕ ∈ L1([y1, y2]), then

2s−1ϕ

(

y1 + y2

2

)

≤1

y2 − y1

∫ y2

y1

ϕ(z)dz ≤ϕ(y1) + ϕ(y2)

s+ 1. (4.2)

If we set k =1

s+ 1, then it is the best possible in the second inequality

in (4.2).

A varation of generalized Hadamard’s inequality which holds for gen-eralized s-convex functions in the second sense [2].

Theorem 4.3. Assume that ϕ : R+ −→ Rα+ is a generalized s-convex func-

tion in the second sense where 0 < s < 1 and y1, y2 ∈ R+ with y1 < y2. Ifϕ ∈ L1([y1, y2]), then

2α(s−1)ϕ

(

y1 + y2

2

)

≤Γ(1 + α)

(y2 − y1)αy1I

(α)y2

ϕ(x)

≤Γ(1 + sα)Γ(1 + α)

Γ(1 + (s+ 1)α)(ϕ(y1) + ϕ(y2)) . (4.3)

12

Page 13: Generalized Convex Functions and Their Applications · The convexity of functions have been widely used in many branches of mathematics, for example in mathematical analysis, function

Proof. We know that ϕ is generalized s-convex in the second sense,whichlead to

ϕ(ηy1 + (1− η)y2) ≤ ηαsϕ(y1) + (1− η)αsϕ(y2),∀η ∈ [0, 1].

Then the following inequality can be written:

Γ(1 + α) 0I(α)1 ϕ(ηy1 + (1− η)y2) ≤ ϕ(y1)Γ(1 + α) 0I

(α)1 ηαs

+ϕ(y2)Γ(1 + α) 0I(α)1 (1− η)αs

=Γ(1 + sα)Γ(1 + α)

Γ(1 + (s+ 1)α)(ϕ(y2) + y2)

By considering z = ηy1 + (1− η)y2. Then

Γ(1 + α) 0I(α)1 ϕ(ηy1 + (1− η)y2) =

Γ(1 + α)

(y1 − y2)αy2I

(α)y1 ϕ(x)

=Γ(1 + α)

(y2 − y1)αy1I

(α)y2

ϕ(z).

Here

Γ(1 + α)

(y2 − y1)αy1I

(α)y2

ϕ(x) ≤Γ(1 + sα)Γ(1 + α)

Γ(1 + (s + 1)α)(ϕ(y1) + ϕ(y2)).

Then, the second inequality in (4.3) is given.

Now

ϕ

(

z1 + z2

2

)

≤ϕ(z1) + ϕ(z2)

2αs,∀z1, z2 ∈ I. (4.4)

Let z1 = ηy1 + (1− η)y2 and z2 = (1− η)y1 + ηy2 with η ∈ [0, 1].Hence, by applying (4.4), the next inequalty holds

ϕ

(

y1 + y2

2

)

≤ϕ(ηy1 + (1− η)y2) + ϕ((1 − η)y1 + ηy2)

2αs, ∀η ∈ [0, 1].

So

1

Γ(1 + α)

∫ 1

(

y1 + y2

2

)

(dη)α ≤1

2α(s−1)(y2 − y1)αy1I

(α)y2

ϕ(z)

Then,

2α(s−1)ϕ

(

y1 + y2

2

)

≤Γ(1 + α)

(y2 − y1)αy1I

(α)y2

ϕ(z).

13

Page 14: Generalized Convex Functions and Their Applications · The convexity of functions have been widely used in many branches of mathematics, for example in mathematical analysis, function

Lemma 4.4. Assume that ϕ : [y1, y2] ⊂ R −→ Rα is a local fractional

derivative of order α (ϕ ∈ Dα) on (y1, y2) with y1 < y2. If ϕ(2α) ∈Cα[y1, y2], then the following equality holds:

Γ(1 + 2α)[Γ(1 + α)]2

2α(y2 − y1)y1I

(α)y2

ϕ(x) −Γ(1 + 2α)

2αϕ

(

y1 + y2

2

)

=(y2 − y1)

16α

[

0I(α)1 γ2αϕ(2α)

(

γy1 + y2

2+ (1− γ)y1

)

+ 0I(α)1 (γ − 1)2αϕ(2α)

(

γy2 + (1− γ)y1 + y2

2

)]

Proof. From the local fractional integration by parts, we get

B1 =1

Γ(1 + α)

∫ 1

0γ2αϕ(2α)

(

γy1 + y2

2+ (1− γ)y1

)

(dγ)α

=

(

2

y2 − y1

ϕ(α)

(

y1 + y2

2

)

−Γ(1 + 2α)

(

2

y2 − y1

)2α

γα ϕ

(

γy1 + y2

2+ (1− γ)y1

)∣

1

0

+Γ(1 + 2α)Γ(1 + α)

(

2

b− a

)2α ∫ 1

(

γy1 + y2

2+ (1− γ)y1

)

(dγ)α

=

(

2

y2 − y1

ϕ(α)

(

y1 + y2

2

)

− Γ(1 + 2α)

(

2

y2 − y1

)2α

ϕ

(

y1 + y2

2

)

+Γ(1 + 2α)Γ(1 + α)

(

2

y2 − y1

)2α ∫ 1

(

γy1 + y2

2+ (1− γ)y1

)

(dγ)α

Setting x = γy1 + y2

2+ (1− γ)y1, for γ ∈ [0, 1] and multiply the both sides

in the last equation by(y2 − y1)

16α, we get

B1 =(y2 − y1)

16α 0I(α)1 γ2αϕ(2α)

(

γy1 + y2

2+ (1− γ)y1

)

=(y2 − y1)

α

8αϕ(α)

(

y1 + y2

2

)

−Γ(1 + 2α)

4αϕ

(

y1 + y2

2

)

+Γ(1 + 2α)Γ(1 + α)

2α(y2 − y1)α

y1+y22

y1

ϕ(x)(dx)α.

14

Page 15: Generalized Convex Functions and Their Applications · The convexity of functions have been widely used in many branches of mathematics, for example in mathematical analysis, function

By the similar way, also we have

B2 =(y2 − y1)

16α 0I(α)1 (γ − 1)2αϕ(2α)

(

γy2 + (1− γ)y1 + y2

2

)

= −(y2 − y1)

α

8αϕ(α)

(

y1 + y2

2

)

−Γ(1 + 2α)

4αϕ

(

y1 + y2

2

)

+Γ(1 + 2α)Γ(1 + α)

2α(y2 − y1)α

∫ y2

y1+y22

ϕ(x)(dx)α.

Thus, adding B1 and B2, we get the desired result.

Theorem 4.5. Assume that ϕ : U ⊂ [0,∞) −→ Rα such that ϕ ∈ Dα

on Int(U) (Int(U) is the interior of U) and ϕ(2α) ∈ Cα[y1, y2], wherey1, y2 ∈ U with y1 < y1. If |ϕ| is generalized s-convex on [y1, y2], for somefixed 0 < s ≤ 1, then the following inequality holds:

Γ(1 + 2α)

2αϕ

(

y1 + y2

2

)

−Γ(1 + 2α)[Γ(1 + α)]2

2α(y2 − y1)αy1I

(α)y2

ϕ(x)

≤(y2 − y1)

16α

{

2αΓ(1 + (s+ 2)α)

Γ(1 + (s + 3)α)

ϕ(2α)

(

y1 + y2

2

)∣

+

[

Γ(1 + sα)

Γ(1 + (s + 1)α)

−2αΓ(1 + (s+ 1)α)

Γ(1 + (s+ 2)α)+

Γ(1 + (s+ 2)α)

Γ(1 + (s+ 3)α)

]

[∣

∣ϕ(2α)(y1)

∣+∣

∣ϕ(2α)(y2)

]

}

(4.5)

≤(y2 − y1)

16α

{

2α(2−s)Γ(1 + (s+ 2)α)

Γ(1 + (s + 3)α)

Γ(1 + sα)Γ(1 + α)

Γ(1 + (s+ 1)α)+

Γ(1 + sα)

Γ(1 + (s+ 1)α)

−2αΓ(1 + (s+ 1)α)

Γ(1 + (s + 2)α)+

Γ(1 + (s+ 2)α)

Γ(1 + (s+ 3)α)

}

[∣

∣ϕ(2α)(y1)

∣+∣

∣ϕ(2α)(y2)

]

. (4.6)

15

Page 16: Generalized Convex Functions and Their Applications · The convexity of functions have been widely used in many branches of mathematics, for example in mathematical analysis, function

Proof. From Lemma 4.4, we have

Γ(1 + 2α)

2αϕ

(

y1 + y2

2

)

−Γ(1 + 2α)[Γ(1 + α)]2

2α(y2 − y1)αy1I

(α)y2

ϕ(x)

≤(y2 − y1)

16α

[

0I(α)1 γ2α

ϕ(2α)(γy1 + y2

2+ (1− γ)y1)

+ 0I(α)1 (γ − 1)2α

ϕ(2α)

(

γy2 + (1− γ)y1 + y2

2

)∣

]

≤(y2 − y1)

16α0I

(α)1 γ2α

[

γαs∣

ϕ(2α)

(

y1 + y2

2

)∣

+ (1− γ)αs∣

∣ϕ(2α)(y1)

]

+(y2 − y1)

16α0I

(α)1 (γ − 1)2α

[

γαs∣

∣ϕ(2α)(y2)

∣+ (1− γ)αs

ϕ(2α)

(

y1 + y2

2

)∣

]

=(y2 − y1)

16α

{

Γ(1 + (s+ 2)α)

Γ(1 + (s+ 3)α)

ϕ(2α)

(

y1 + y2

2

)∣

+

[

Γ(1 + αs)

Γ(1 + (s+ 1)α)− 2α

Γ(1 + (s+ 1)α)

Γ(1 + (s+ 2)α)+

Γ(1 + (s+ 2)α)

Γ(1 + (s+ 3)α)

]

∣ϕ(2α)(y1)

}

+(y2 − y1)

16α

{

Γ(1 + (s+ 2)α)

Γ(1 + (s+ 3)α)

ϕ(2α)

(

y1 + y2

2

)∣

+

[

Γ(1 + αs)

Γ(1 + (s+ 1)α)− 2α

Γ(1 + (s+ 1)α)

Γ(1 + (s+ 2)α)+

Γ(1 + (s+ 2)α)

Γ(1 + (s+ 3)α)

]

∣ϕ(2α)(a2)

+Γ(1 + (s+ 2)α)

Γ(1 + (s+ 3)α)

ϕ(2α)

(

y1 + y2

2

)∣

}

=(y2 − y1)

16α

{

2αΓ(1 + (s+ 2)α)

Γ(1 + (s+ 3)α)

ϕ(2α)

(

y1 + y2

2

)∣

+

[

Γ(1 + sα)

Γ(1 + (s+ 1)α)

−2αΓ(1 + (s+ 1)α)

Γ(1 + (s+ 2)α)+

Γ(1 + (s+ 1)α)

Γ(1 + (s+ 3)α)

]

[∣

∣ϕ(2α)(y1)

∣+∣

∣ϕ(2α)(y2)

]

}

.

This proves inequality (4.5). Since

2α(s−1)ϕ(2α)

(

y1 + y2

2

)

≤Γ(1 + sα)Γ(1 + α)

Γ(1 + (s+ 1)α)

(

ϕ(2α)(y1) + ϕ(2α)(y2))

,

16

Page 17: Generalized Convex Functions and Their Applications · The convexity of functions have been widely used in many branches of mathematics, for example in mathematical analysis, function

then∣

Γ(1 + 2α)

2αϕ

(

y1 + y2

2

)

−Γ(1 + 2α)[Γ(1 + α)]2

2α(y2 − y1)αy1I

(α)y2

ϕ(x)

≤(y2 − y1)

16α

{

2αΓ(1 + (s+ 2)α)

Γ(1 + (s+ 3)α)

2−α(s−1)Γ(1 + sα)Γ(1 + α)

Γ(1 + (s+ 1)α)

[∣

∣ϕ(2α)(y1)

∣+∣

∣ϕ(2α)(y2)

]

+

[

Γ(1 + sα)

Γ(1 + (s+ 1)α)−

2αΓ(1 + (s+ 1)α)

Γ(1 + (s+ 2)α)+

Γ(1 + (s+ 2)α)

Γ(1 + (s+ 3)α)

]

[∣

∣ϕ(2α)(y1)

∣+∣

∣ϕ(2α)(y2)

]

}

=(y2 − y1)

16α

{

2α(2−s)Γ(1 + (s + 2)α)

Γ(1 + (s+ 3)α)

Γ(1 + sα)Γ(1 + α)

Γ(1 + (s+ 1)α)+

Γ(1 + sα)

Γ(1 + (s+ 1)α)

−2αΓ(1 + (s+ 1)α)

Γ(1 + (s+ 2)α)+

Γ(1 + (s+ 2)α)

Γ(1 + (s+ 3)α)

[∣

∣ϕ(2α)(y1)

∣+∣

∣ϕ(2α)(y2)

]

}

Thus, we get the inequality (4.6)and the proof is complete.

Remark 4.6. 1. When α = 1, Theorem 4.5 reduce to Theorem 2 in[21].

2. If s = 1 in Theorem 4.5 , then

Γ(1 + 2α)

2αϕ

(

y1 + y2

2

)

−Γ(1 + 2α)[Γ(1 + α)]2

2α(y2 − y1)αy1I

(α)y2

ϕ(x)

≤(y2 − y1)

16α

{

2αΓ(1 + 3α)

Γ(1 + 4α)

ϕ(2α)

(

y1 + y2

2

)∣

+

[

Γ(1 + α)

Γ(1 + 2α)

−2αΓ(1 + 2α)

Γ(1 + 3α)+

Γ(1 + 3α)

Γ(1 + 4α)

]

[∣

∣ϕ(2α)(y1)

∣+∣

∣ϕ(2α)(y2)

]

}

≤(y2 − y1)

16α

{

2αΓ(1 + 3α)

Γ(1 + 4α)

[Γ(1 + α)]2

Γ(1 + 2α)+

Γ(1 + α)

Γ(1 + 2α)

−2αΓ(1 + 2α)

Γ(1 + 3α)+

Γ(1 + 3α)

Γ(1 + 4α)

}

[∣

∣ϕ(2α)(y1)

∣+∣

∣ϕ(2α)(y2)

]

.(4.7)

3. If s = 1 and α = 1 in Theorem 4.5, then

ϕ

(

y1 + y2

2

)

−1

y2 − y1

∫ y2

y1

ϕ(x)dx

≤(y2 − y1)

2

192

{

6

ϕ′′

(

y1 + y2

2

)∣

+∣

∣ϕ′′(y1)∣

∣+∣

∣ϕ′′(y2)∣

}

≤(y2 − y1)

2

48

{∣

∣ϕ′′(y1)∣

∣+∣

∣ϕ′′(y2)∣

}

17

Page 18: Generalized Convex Functions and Their Applications · The convexity of functions have been widely used in many branches of mathematics, for example in mathematical analysis, function

We give a new upper bound of the left generalized Hadamard’s inequal-ity for generalized s-convex functions in the following theorem:

Theorem 4.7. Assume that ϕ : U ⊂ [ 0,∞) −→ Rα such that ϕ ∈ Dα on

Int(U) and ϕ(2α) ∈ Cα[y1, y2], where y1, y2 ∈ U with y1 < y2. If |ϕ(2α)|p2 isgeneralized s-convex on [y1, y2], for some fixed 0 < s ≤ 1 and p2 > 1 with1p1

+ 1p2

= 1, then the following inequality holds:

Γ(1 + 2α)

2αϕ

(

y1 + y2

2

)

−Γ(1 + 2α)[Γ(1 + α)]2

2α(y2 − y1)αy1I

(α)y2

ϕ(x)

≤(y2 − y1)

16α

[

Γ(1 + sα)

Γ(1 + (s+ 1)α)

]1p2

[

Γ(1 + 2p1α)

Γ(1 + (2p1 + 1)α)

]1p1

×

[

(∣

ϕ(2α)

(

y1 + y2

2

)∣

p2

+∣

∣ϕ(2α)(y1)

p2)

1p2

+

(∣

ϕ(2α)

(

y1 + y2

2

)∣

p2

+∣

∣ϕ(2α)(y2)

p2)

1p2

]

. (4.8)

Proof. Let p1 > 1, then from Lemma 4.4 and using generalized Holder’sinequality [27], we obtain

Γ(1 + 2α)

2αϕ

(

y1 + y2

2

)

−Γ(1 + 2α)[Γ(1 + α)]2

2α(y2 − y1)αy1I

(α)y2

ϕ(x)

≤(y2 − y1)

16α

{

0I(α)1 γ2α

ϕ(2α)

(

γy1 + y2

2+ (1− γ)y1

)∣

+0I(α)1 (γ − 1)2α

ϕ(2α)

(

γy2 + (1− γ)y1 + y2

2

)∣

}

≤(y2 − y1)

16α

(

0I(α)1 γ2p1α

)1p1

×

(

0I(α)1

ϕ(2α)

(

γy1 + y2

2+ (1− γ)y1

)∣

p2)

1p2

+(y2 − y1)

16α

(

0I(α)1 (1− γ)2p1α

)1p1

×

(

0I(α)1

ϕ(2α)

(

γy2 + (1− γ)y1 + y2

2

)∣

p2)

1p2

.

18

Page 19: Generalized Convex Functions and Their Applications · The convexity of functions have been widely used in many branches of mathematics, for example in mathematical analysis, function

Since∣

∣ϕ(2α)∣

p2is generalized s-convex, then

0I(α)1

ϕ(2α)

(

γy1 + y2

2+ (1− γ)y1

)∣

p2

≤Γ(1 + sα)

Γ(1 + (s+ 1)α)

ϕ(2α)

(

y1 + y2

2

)∣

p2

+Γ(1 + sα)

Γ(1 + (s + 1)α)

∣ϕ(2α)(y1)

p2,

which means

0I(α)1

ϕ(2α)

(

γy2 + (1− γ)y1 + y2

2

)∣

p2

≤Γ(1 + sα)

Γ(1 + (s+ 1)α)

∣ϕ(2α)(y2)

p2

+Γ(1 + sα)

Γ(1 + (s+ 1)α)

ϕ(2α)

(

y1 + y2

2

)∣

p2

.

Hence∣

Γ(1 + 2α)

2αϕ

(

y1 + y2

2

)

−Γ(1 + 2α)[Γ(1 + α)]2

2α(y2 − y1)αy1I

(α)y2

ϕ(x)

≤(y2 − y1)

16α

[

Γ(1 + sα)

Γ(1 + (s+ 1)α)

]1p2

[

Γ(1 + 2p1α)

Γ(1 + (2p1 + 1)α)

]1p1

×

{

[∣

ϕ(2α)

(

y1 + y2

2

)∣

p2

+∣

∣ϕ(2α)(y1)

p2]

1p2

+

[∣

ϕ(2α)

(

y1 + y2

2

)∣

p2

+∣

∣ϕ(2α)(y2)

p2]

1p2

}

.

The proof is complete.

Remark 4.8. If s = 1 in Theorem 4.7, then∣

Γ(1 + 2α)

2αϕ

(

y1 + y2

2

)

−Γ(1 + 2α)[Γ(1 + α)]2

2α(y2 − y1)αy1I

(α)y2

ϕ(x)

≤(y2 − y1)

16α

[

Γ(1 + α)

Γ(1 + 2α)

]1p2

[

Γ(1 + 2p1α)

Γ(1 + (2p1 + 1)α)

]1p1

×

{

[∣

ϕ(2α)

(

y1 + y2

2

)∣

p2

+∣

∣ϕ(2α)(y1)

p2]

1p2

+

[∣

ϕ(2α)

(

y1 + y2

2

)∣

p2

+∣

∣ϕ(2α)(y2)

p2]

1p2

}

. (4.9)

19

Page 20: Generalized Convex Functions and Their Applications · The convexity of functions have been widely used in many branches of mathematics, for example in mathematical analysis, function

Corollary 4.9. Assume that ϕ : U ⊂ [0,∞) −→ Rα such that ϕ ∈ Dα on

Int(U) and ϕ(2α) ∈ Cα[y1, y2], where y1, y2 ∈ U with y1 < y1. If |ϕ(2α)|p2 isgeneralized s-convex on [y1, y2], for some fixed 0 < s ≤ 1 and p2 > 1 with1p1

+ 1p2

= 1, then the following inequality holds:

Γ(1 + 2α)

2αϕ

(

y1 + y2

2

)

−Γ(1 + 2α)[Γ(1 + α)]2

2α(y2 − y1)αy1I

(α)y2

ϕ(x)

≤(y2 − y1)

16α[Γ(1 + sα)]

1p2

[Γ(1 + (s+ 1)α)]2p2

[

Γ(1 + 2p1α)

Γ(1 + (2p1 + 1)α)

]1p1

×

{[

(

2α(1−s)Γ(1 + sα)Γ(1 + α) + Γ(1 + (s+ 1)α))

1p2

+2α(1−s)

p2 [Γ(1 + α)]1p2 [Γ(1 + α)]

1p2

]

[∣

∣ϕ(2α)(y1)

∣+∣

∣ϕ(2α)(y2)

]

}

Proof. Since∣

∣ϕ(2α)∣

p2is generalized s-convex, then

2α(s−1)ϕ(2α)

(

y1 + y2

2

)

≤Γ(1 + sα)Γ(1 + α)

Γ(1 + (s+ 1)α)

(

ϕ(2α)(y1) + ϕ(2α)(y2))

.

Hence using (4.8), we get

Γ(1 + 2α)

2αϕ

(

y1 + y2

2

)

−Γ(1 + 2α)[Γ(1 + α)]2

2α(y2 − y1)αy1I

(α)y2

ϕ(x)

≤(y2 − y1)

16α[Γ(1 + sα)]

1p2

[Γ(1 + (s+ 1)α)]2p2

[

Γ(1 + 2p1α)

Γ(1 + (2p1 + 1)α)

]1p1

×{[(

2α(1−s)Γ(1 + sα)Γ(1 + α) + Γ(1 + (s + 1)α))

|ϕ(2α)(y1)|p2

+2α(1−s)Γ(1 + sα)Γ(1 + α)|ϕ(2α)(y2)|p2]

1p2

+[

2α(1−s)Γ(1 + sα)Γ(1 + α)|ϕ(2α)(y1)|p2

+(

2α(1−s)Γ(1 + sα)Γ(1 + α) + Γ(1 + (s+ 1)α))

|ϕ(2α)(y2)|p2]

1q

}

and since

k∑

i=1

(xi + zi)αn ≤

k∑

i=1

xαni +

k∑

i=1

zαni

20

Page 21: Generalized Convex Functions and Their Applications · The convexity of functions have been widely used in many branches of mathematics, for example in mathematical analysis, function

for 0 < n < 1, xi, zi ≥ 0;∀1 ≤ i ≤ k, then we have

Γ(1 + 2α)

2αϕ

(

y1 + y2

2

)

−Γ(1 + 2α)[Γ(1 + α)]2

2α(y2 − y1)αy1I

(α)y2

ϕ(x)

≤(y2 − y1)

16α[Γ(1 + sα)]

1p2

[Γ(1 + (s + 1)α)]2p2

[

Γ(1 + 2p1α)

Γ(1 + (2p1 + 1)α)

]1p1

×

{[

(

2α(1−s)Γ(1 + sα)Γ(1 + α) + Γ(1 + (s + 1)α))

1p2

∣ϕ(2α)(y1)

+2α(1−s)

p2 [Γ(1 + sα)]1p2 [Γ(1 + α)]

1p2

∣ϕ(2α)(y2)

]

+

[

2α(1−s)

p2 [Γ(1 + sα)]1p2 [Γ(1 + α)]

1p2

∣ϕ(2α)(y1)

+(

2α(1−s)Γ(1 + sα)Γ(1 + α) + Γ(1 + (s+ 1)α))

1p2

∣ϕ(2α)(y2)

]}

where 0 < 1p2

< 1 for p2 > 1. By a simple calculation, we obtain therequired result.

Now, the generalized Hadamard’s type inequality for generalized s-concave functions.

Theorem 4.10. Assume that ϕ : U ⊂ [0,∞) −→ Rα such that ϕ ∈ Dα on

Int(U) and ϕ(2α) ∈ Cα[y1, y2], where y1, y2 ∈ U with y1 < y1. If |ϕ(2α)|p2 is

generalized s-convex on [y1, y2], for some fixed 0 < s ≤ 1 and p2 > 1 with1p1

+ 1p2

= 1, then the following inequality holds:

Γ(1 + 2α)

2αϕ

(

y1 + y2

2

)

−Γ(1 + 2α) [Γ(1 + α)]2

2α(y2 − y1)αy1I

(α)y2

ϕ(x)

≤2

α(s−1)p2 (y2 − y1)

16α (Γ(1 + α))1p2

[

Γ(1 + 2p1α)

Γ(1 + (2p1 + 1)α)

]1p1

×

[∣

ϕ(2α)

(

3y1 + y2

4

)∣

+

ϕ(2α)

(

y1 + 3y24

)∣

]

21

Page 22: Generalized Convex Functions and Their Applications · The convexity of functions have been widely used in many branches of mathematics, for example in mathematical analysis, function

Proof. From Lemma 4.4 and using the generalized Holder inequality forp2 > 1 and 1

p1+ 1

p2= 1, we get

Γ(1 + 2α)

2αϕ

(

y1 + y2

2

)

−Γ(1 + 2α) [Γ(1 + α)]2

2α(a2 − a1)αy1I

(α)y2

ϕ(x)

≤(y2 − y1)

16α

[

0I(α)1 γ2α

ϕ(2α)

(

γy1 + y2

2+ (1− γ)y1

)∣

+ 0I(α)1 (γ − 1)2α

ϕ(2α)

(

γy2 + (1− γ)y1 + y2

2

)∣

]

≤(y2 − y1)

16α

(

0I(α)1 γ2p1α

)1p1

(

0I(α)1

ϕ(2α)

(

γy1 + y2

2+ (1− γ)y1

)∣

p2)

1p2

+(y2 − y1)

16α

(

0I(α)1 (γ − 1)2p1α

)1p1

(

0I(α)1

ϕ(2α)

(

γy2 + (1− γ)y1 + y2

2

)∣

p2)

1p2

.

Since∣

∣ϕ(2α)∣

p2is generalized s-concave, then

0I(α)1

ϕ(2α)

(

γy1 + y2

2+ (1− γ)y1

)∣

p2

≤2α(s−1)

Γ(1 + α)

ϕ(2α)

(

3y1 + y2

4

)∣

p2

(4.10)

also

0I(α)1

ϕ(2α)

(

γy2 + (1− γ)y1 + y2

2

)∣

p2

≤2α(s−1)

Γ(1 + α)

ϕ(2α)

(

y1 + 3y24

)∣

p2

.(4.11)

From (4.10) and (4.11), we observe that

Γ(1 + 2α)

2αϕ

(

y1 + y2

2

)

−Γ(1 + 2α) [Γ(1 + α)]2

2α(y2 − y1)αy1I

(α)y2

ϕ(x)

≤(y2 − y1)

16α

[

Γ(1 + 2p1α)

Γ(1 + (2p1 + 1)α)

]1p1 2

α(s−1)p2

(Γ(1 + α))1p2

ϕ(2α)

(

3y1 + y2

4

)∣

+(y2 − y1)

16α

[

Γ(1 + 2p1α)

Γ(1 + (2p1 + 1)α)

]1p1 2

α(s−1)p2

(Γ(1 + α))1p2

ϕ(2α)

(

y1 + 3y24

)∣

=2

α(s−1)p2 (y2 − y1)

16α (Γ(1 + α))1p2

[

Γ(1 + 2p1α)

Γ(1 + (2p1 + 1)α)

]1p1

[∣

ϕ(2α)

(

3y1 + y2

4

)∣

+

ϕ(2α)

(

y1 + 3y24

)∣

]

the proof is complete.

22

Page 23: Generalized Convex Functions and Their Applications · The convexity of functions have been widely used in many branches of mathematics, for example in mathematical analysis, function

Remark 4.11. 1. If α = 1 in Theorem 4.10, then∣

ϕ

(

y1 + y2

2

)

−1

y2 − y1

∫ y2

y1

ϕ(x)dx

≤2

s−1q (y2 − y1)

2

16

[

1

Γ(2p1 + 1)

]1p1

[∣

ϕ′′

(

3y1 + y2

4

)∣

+

ϕ′′

(

y1 + 3y24

)∣

]

2. If s = 1 and 13 <

[

Γ(1+2p1α)Γ(1+(2p1+1)α)

]1p1 < 1, p1 > 1 in Theorem 4.10,

then∣

Γ(1 + 2α)

2αϕ

(

y1 + y2

2

)

−Γ(1 + 2α) [Γ(1 + α)]2

2α(y2 − y1)αy1I

(α)y2

ϕ(x)

≤(y2 − y1)

16α (Γ(1 + α))1p2

[∣

ϕ(2α)

(

3y1 + y2

4

)∣

+

ϕ(2α)

(

y1 + 3y24

)∣

]

5 Applications to special means

As in [22], some generalized means are considered such as :

A(y1, y2) =yα1 +yα2

2α , y1, y2 ≥ 0;

Ln(y1, y2) =[

Γ(1+nα)Γ(1+(n+1)α)

(

y(n+1)α2 − y

(n+1)α1

)]1n, n ∈ Z{−1, 0}, y1, y2 ∈

R, y1 6= y2.

In [14], the following example was given:let 0 < s < 1 and yα1 , y

α2 , y

α3 ∈ R

α. Defining for x ∈ R+,

ϕ(b) =

{

yα1 b = 0,

yα2 bsα + yα3 b > 0.

If yα2 ≥ 0α and 0α ≤ yα3 ≤ yα1 , then ϕ ∈ GK2s .

Proposition 5.1. Let 0 < y1 < y2 and s ∈ (0, 1). Then∣

Γ(1 + 2α)

2αAs(y1, y2)−

Γ(1 + 2α) [Γ(1 + α)]2

2α(y2 − y1)αLss(y1, y2)

≤(y2 − y1)

16α

Γ(1 + sα)

Γ(1 + (s− 2)α)

{

2αΓ(1 + 3α) [Γ(1 + α)]2

Γ(1 + 4α)Γ(1 + 2α)

+Γ(1 + α)

Γ(1 + 2α)−

2αΓ(1 + 2α)

Γ(1 + 3α)+

Γ(1 + 3α)

Γ(1 + 4α)

}

[

|y1|(s−2)α + |y2|

(s−2)α]

23

Page 24: Generalized Convex Functions and Their Applications · The convexity of functions have been widely used in many branches of mathematics, for example in mathematical analysis, function

Proof. The result follows from Remark 4.7 (2) with ϕ : [0, 1] −→ [0α, 1α],ϕ(x) = xsα. and when α = 1, we have the following inequalitly:

As(y1, y2)−1

y2 − y1Lss(y1, y2)

≤(y2 − y1)

2|s(s− 1)|

48

{

|y1|s−2 + |y2|

s−2}

.(5.1)

Proposition 5.2. Let 0 < y1 < y2 and s ∈ (0, 1). Then

Γ(1 + 2α)

2αAs(y1, y2)−

Γ(1 + 2α) [Γ(1 + α)]2

2α(y2 − y1)αLss(y1, y2)

≤(y2 − y1)

16α

[

Γ(1 + α)

Γ(1 + 2α)

]1p2

Γ(1 + sα)

Γ(1 + (s− 2)α)

[

Γ(1 + 2p1α)

Γ(1 + (2p1 + 1)α)

]1p1

×

(

y1 + y2

2

(s−2)p2α

+ |y1|(s−2)p2α

)1p2

+

(

y1 + y2

2

(s−2)p2α

+ |y2|(s−2)p2α

)1p2

,

where p2 > 1 and 1p1

+ 1p2

= 1.

Proof. The result follows (4.9) with ϕ : [0, 1] −→ [0α, 1α], ϕ(x) = xsα, andwhen α = 1, we have the following inequalitly:

As(y1, y2)−1

y2 − y1Lss(y1, y2)

≤(y2 − y1)

2|s(s− 1)|

21p2 16(2p1 + 1)

1p1

(

y1 + y2

2

(s−2)p2

+ |y1|(s−2)p2

)1p2

+

(

y1 + y2

2

(s−2)p2

+ |y2|(s−2)p2

)1p2

. (5.2)

Where A(y1, y2) and Ln(y1, y2) in (5.1) and (5.2) are known as

1. Arithmetic mean:

A(y1, y2) =y1 + y2

2, y1, y2 ∈ R

+;

24

Page 25: Generalized Convex Functions and Their Applications · The convexity of functions have been widely used in many branches of mathematics, for example in mathematical analysis, function

2. Logarithmic mean :

L(y1, y2) =y1 − y2

ln |y1| − ln |y2|, |y1| 6= y2, y1, a2 6= 0, y1, y2 ∈ R

+;

Generalized Log-mean:

Ln(y1, y2) =

[

yn+12 − yn+1

1

(n+ 1)(y2 − y1)

]

1n

, n ∈ Z \ {−1, 0} , y1, y2 ∈ R+.

Now, we give application to wave equation on Cantor sets:the wave equation on Cantor sets (local fractional wave equation) was givenby [27]

∂2αf(x, t)

∂t2α= A2α ∂

2αf(x, t)

∂x2α(5.3)

Following (5.3), a wave equation on Cantor sets was proposed as follows[29]:

∂2αf(x, t)

∂t2α=

x2α

Γ(1 + 2α)

∂2αf(x, t)

∂x2α, 0 ≤ α ≤ 1 (5.4)

where f(x, t) is a fractal wave function and the initial value is given by

f(x, 0) =xα

Γ(1 + α). The solution of (5.4) is given as

f(x, t) =xα

Γ(1 + α)+

t2α

Γ(1 + 2α).

By using (4.4), we have

Γ(1 + 2α)Γ(1 + α)

2α(y2 − y1)α

∫ y2

y1

f(x, t)(dt)α −Γ(1 + 2α)

2αf

(

x,y1 + y2

2

)

=(y2 − y1)

α

8αΓ(1 + 2α)

[

(

2

y2 − y1

)2α

y1I(α)y2+y1

2

(t− y1)2αx2α

∂2αf(x, t)

∂xα

+ y1I(α)y2+y1

2

(

2(t− y1)

y2 − y1− 1

)2α

x2α∂2αf(x, t)

∂xα

]

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