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1. Introduction
For a fixed prime , it is always possible to write a nonzero rational number in the form , where is not divisible by and is an integer. The -adic norm is defined as . The -adic norm fulfills all the properties of a real norm along with a stronger inequality:
The completion of the field of rational number with respect to leads to the field of -adic numbers . In [1], it can be seen that any can be represented in the formal power series form aswhere . The convergence of series (2) is followed from .
The -dimensional vector space consists of tuples , where , with the following norm:
The ball and the corresponding sphere with center at and radius in non-Archimedean geometry are given by
When , we write .
Since the space is locally compact commutative group under addition, it cements the fact from the standard analysis that there exists a translation invariant Haar measure . Also, the measure is normalized bywhere represents the Haar measure of a measurable subset of . Furthermore, one can easily show that , , for any .
The last several decades have seen a growing interest in the -adic models appearing in various branches of science. The -adic analysis has cemented its role in the field of mathematical physics (see, for example, [2–4]). Many researchers have also paid relentless attention to harmonic analysis in the -adic fields [5–11]. The present paper can be considered as an extension of investigation of Hardy-type operators started in [6, 7, 12–16].
The one-dimensional Hardy operatorwas introduced by Hardy in [17] for measurable functions which satisfies the inequalitywhere the constant is sharp. In [18], Faris proposed an extension of an operator on higher dimensional space bywhere for . In addition, Christ and Grafakos [23] obtained the exact value of the norm of an operator defined by (8). Over the years, Hardy operator has gained a significant amount of attention due to its boundedness properties [19–22]. For complete understanding of Hardy-type operators, we refer the interested readers to study [12, 23–29] and the references therein.
In what follows, the -dimensional -adic fractional Hardy operatorwas defined and studied for and in [15]. When , the operator transfers to the -adic Hardy operator (see [30] for more details). Fu et al. in [30] acquired the optimal bounds of -adic Hardy operator on . On the central Morrey spaces, the -adic Hardy-type operators and their commutators are discussed in [16]. In this link, see also [6, 7, 14, 27].
From now on, we turn our attention towards the rough kernel version of an operator which recently received a substantial attention in analysis (see for instance [11, 31–37]). The roughness of Hardy operator was first time studied by Fu et al. in [12]. Motivated from the results of rough Hardy-type operators in Euclidean space, we define a special kind of rough fractional Hardy operator and its commutator in the -adic field.
Let , and be measurable functions and let . Then, for , we define a rough -adic fractional Hardy operator and its commutator asandwhenever
Remark 1.
Obviouslyholds for every integer and prime . Since the inclusionholds and is a linear space over field , the product is correctly defined. Moreover, if a nonzero has a form and(see (2)), then there is such thatwhenever . Using (3), we obtain . Now from (16) and (17), it follows that
Thus, for every nonzero , the vector belongs to the sphere
From (12), it directly follows that for every nonzero , and using (12) and (13), we havefor every . Consequently, the operators and are correctly defined.
The aim of the present paper is to study the weighted central mean oscillations and weighted -adic Lipschitz estimates of on weighted -adic function spaces like weighted -adic Lebesgue spaces, weighted -adic Herz spaces and -adic Herz–Morrey spaces. Throughout this article, the letter represents a constant whose value may differ at all of its occurrence. Before turning to our key results, let us define and denote the relevant -adic function spaces.
2. Notations and Definitions
Suppose is a weight function on , which is non-negative and locally integrable function on . The weighted measure of is denoted and defined as . Let be the space of all complex-valued functions on such that
Definition 1.
Suppose and is a weight function. The -adic space is defined as follows:where
Definition 2.
(see [5]). Suppose , and and are weight functions. Then, the weighted -adic Herz space is defined bywhereand is the characteristic function of the sphere .
Remark 2.
Obviously .
Definition 3.
(see [5]). Let , , and be weight functions and be a non-negative real number. Then, the weighted -adic Herz–Morrey space is defined as follows:where
Remark 3.
It is evident that .
Now, we define the weighted -adic Lipschitz space.
Definition 4.
Suppose , and is a weight function. The -adic space is defined aswhere
Muckenhoupt introduced the theory of weights on in [38]. Let us define the weights in the -adic field.
Definition 5.
A weight function , if there exists a constant free from choice of such that
For the case , we havefor every .
Remark 4.
A weight function if it undergoes the stipulation of weights.
3. Weighted Estimates of on Weighted -Adic Herz-Type Spaces
The present section discusses the boundedness of on weighted -adic Lebesgue spaces as well as on the weighted -adic Herz-type spaces. We begin the section with some useful lemmas to prove our main results.
Lemma 1.
(see [39]). Suppose ; then, there exists constants and such thatfor measurable subset of a ball .
Remark 5.
If , then it follows from Lemma 1 that there exists a constant and such that as and as .
Lemma 2.
Suppose and ; then, there is a constant such that for , ,
Proof.
Firstly, we consider
We assume without loss of generality that ; then, using Lemma 1, we are down to
Lemma 3.
Suppose ; thenfor ,where .
Proof.
Since , satisfies the conditionsfor every .
From here, we easily get
Theorem 1.
Let , , ; thenholds for all , , and .
Now we state the results about the boundedness of commutator of rough -adic fractional Hardy operator on weighted -adic Herz-type spaces.
Theorem 2.
Let , and let , .
If , then the inequalityholds for all , , and .
Remark 6.
If , then Theorem 1 becomes a special case of Theorem 2.
Theorem 3.
Let , and let , and . If , thenholds for all , , and .
Proof.
of Theorem 2. By definition, we firstly have
For with , we get
Also, since , by the application of Hölder’s inequality together with Lemma 3, we have
To estimate , we make use of Hölder’s inequality, Remark 5, and along with (43) and (44) to have
Now, we turn our attention towards estimating .
In order to evaluate , we need the following preparation. Apply Hölder’s inequality at the outset to deduce
We imply Hölder’s inequality, inequality (47), Lemma 3, and Remark 5 to estimate .
In a similar fashion, we can estimate . Using Hölder’s inequality, Lemmas 2 and 3, Remark 5, and inequality (44), we get
From (45), (48), and (49) together with Jensen inequality, we have
Consequently,
From here on in the proof we consider couple of cases, and .
Case 1.
When , noticing that , we proceed as follows.
Case 2.
When , applying Hölder’s inequality with , we get
Therefore, the proof of theorem is completed.
Proof.
of Theorem 3. From Theorem 2, we have
By definition of weighted -adic Herz–Morrey space and Jensen inequality together with , and , it follows that
4. Weighted Lipschitz Estimates for the Commutator of Rough -Adic Fractional Hardy Operator on Herz–Morrey Spaces
In this section, we obtain the weighted -adic Lipschitz estimates for the commutator of rough -adic fractional Hardy operator on -adic Lebesgue spaces and -adic Herz-type spaces. We begin the section with a useful lemma which can be proved in the similar lines as Lemma 2.
Lemma 5.
Suppose and ; then, there is a constant such that for , ,
Theorem 4.
Let , , , ; then,holds for all , , , and .
Now we state the results about the boundedness of commutator of rough -adic fractional Hardy operator on weighted -adic Herz-type spaces.
Theorem 5.
Let , , and let , If , then the inequalityholds for all , , , and .
Remark 7.
If and , then Theorem 4 can easily be obtained from Theorem 5.
Theorem 6.
Let , , and let , , and If , thenholds for all , , , and .
Proof.
of Theorem 5. Following the same pattern of Theorem 2, we have
To estimate , we make use of Hölder’s inequality, Remark 5, , , and along with (43) and (44) to have
For the estimation of , we need to decompose it as
We need the following preparation to estimate . Apply Hölder’s inequality to get
We imply Hölder’s inequality, inequality (63), Lemma 3, and Remark 5 to estimate .
Now we turn towards . Using once again Hölder’s inequality, Lemmas 5 and 3, Remark 5, and inequality (44), we get
Rest of the proof is similar to the proof of Theorem 2. Thus, we come to an end of proof.
Proof.
of Theorem 6. Let . By the definition of weighted -adic Herz–Morrey spaces along with inequalities (61), (64), and (65), we are down to
Next by applying the similar arguments as in Theorem 3, we get
Therefore, we conclude the proof.
Authors’ Contributions
All authors made equal contributions and read and supported the last original copy.
Acknowledgments
This research was funded by the Deanship of Scientific Research at Princess Nourah Bint Abdulrahman University through the Fast-Track Research Funding Program.
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