Abstract
The interactions between topological covering spaces, homotopy and group structures in a fibered space exhibit an array of interesting properties. This paper proposes the formulation of finite covering space components of compact Lindelof variety in topological (C, R) spaces. The covering spaces form a Noetherian structure under topological injective embeddings. The locally path-connected components of covering spaces establish a set of finite topological groups, maintaining group homomorphism. The homeomorphic topological embedding of covering spaces and base space into a fibered non-compact topological (C, R) space generates two classes of fibers based on the location of identity elements of homomorphic groups. A compact general fiber gives rise to the discrete variety of fundamental groups in the embedded covering subspace. The path-homotopy equivalence is admitted by multiple identity fibers if, and only if, the group homomorphism is preserved in homeomorphic topological embeddings. A single identity fiber maintains the path-homotopy equivalence in the discrete fundamental group. If the fiber is an identity-rigid variety, then the fiber-restricted finite and symmetric translations within the embedded covering space successfully admits path-homotopy equivalence involving kernel. The topological projections on a component and formation of 2-simplex in fibered compact covering space embeddings generate a prime order cyclic group. Interestingly, the finite translations of the 2-simplexes in a dense covering subspace assist in determining the simple connectedness of the covering space components, and preserves cyclic group structure.
MSC:
54B40; 54C25; 55P10; 55R15
1. Introduction
The structures and properties of topological covering space of any arbitrary base space have been studied in detail by Lubkin [1]. The construction of covering space of an arbitrary base space is formulated without any requirement of additional local as well as global topological properties, such as path connectedness. In general, if a continuous surjection between two spaces is given by then is a locally trivial sheaf [1]. If the local connectedness of the topological space is further relaxed then such that the covering space may not be uniquely determined, and as a result the suitable decomposition is necessary where condition is preserved (Note that denotes an index set and each is open). In another extreme let us consider the compact-open topology in the spaces of continuous functions represented by between the topological spaces . Suppose we consider the open subbases given by where is compact and . In this case the topological properties of are preserved by . Interestingly, if the continuous surjection is a covering projection and the function is defined as , then the function is also a covering map if, and only if, is Hausdorff and contractible (i.e., compact CW-complex with finitely many components) [2]. The characterizations of Hausdorff topological spaces can be made by employing the concept of compact-covering maps, which is analogous to the definition of sequence-covering maps [3]. Note that such covering projective spaces can successfully admit fibrations and injective embeddings. The preservation of fibrations in a covering space and projection requires specific topological properties. For example, if a topological space is locally compact then the preservation of covering fibration is maintained by the local homotopy of the respective topological space [4]. A topological space can admit a class of coverable topological groups by generalizing the concept of cover if the corresponding topological space is of a metrizable and connected variety [5].
This paper investigates the nature of interactions between homeomorphically embedded covering spaces of Lindelof as well as Noetherian variety (under topological injective embeddings) and the finite topological groups within the covering spaces under fibration. The topological properties of corresponding structures and interactions are presented in detail, in view of algebraic as well as geometric topology. First we present the associated concepts and the resulting motivation as well as the summary of contributions made in this paper to address the wider audience. Note that in this paper denotes an index set and represents that the structures and are homeomorphic to each other. Moreover, the sets of extended real numbers, complex numbers and positive integers are denoted as and respectively. The topological spaces under consideration in this paper are second-countable Hausdorff spaces. Furthermore, the topological space under a closed 2-simplex is denoted by whereas denotes an open 2-simplex, and if are two continuous paths, then represents homotopy class path products, where and the relation represents a path-homotopy equivalence.
Motivation and Contributions
It is known that the Poincare group displays a set of interactive properties in the topological covering spaces. It is noted that every filtered Galois group is isomorphic to the corresponding Poincare filtered group of regular covering space where the topological space is a connected variety [1]. Moreover in a covering projection if a connected topological group exists in the simply connected base space then there is a connected covering space group such that preserves respective covering projection properties while incorporating group homomorphism [6]. Interestingly, the varieties of Hausdorff and contractible topological spaces of continuous functions admit fibrations and topological embeddings under injective inclusions [2]. Recall that the covering spaces are generally considered to be path-connected topological spaces. There is a natural way to establish fibrations in a path-connected space . If denotes the space of every path in a path-connected topological space then there is a natural fibration given by such that where is continuous [7]. However a discretely fibered covering space can also be formulated in a covering projection [8]. These observations suggest the importance of investigating the properties of interactions of topological groups and covering spaces under embeddings in a fibered topological space which admits Noetherian convex P-separations [9,10]. Hence, the motivating questions can be summarized as: (1) what are the properties of interactions between the topological groups in homeomorphically embedded compact Lindelof–Noetherian planar covering spaces and the fibers in a path connected subspace, (2) is it possible to categorize the fibers in such covering spaces to establish a topological structure in path-connected embeddings in a space, and (3) what are the properties of generated planar simplicial complexes in view of geometric topology within the respective embedded covering spaces under fibration? These questions are addressed in this paper in relative detail.
The main contributions made in this paper can be summarized as follows. The concepts related to compact Lindelof as well as finite Noetherian (under topological injective embeddings) covering space components are introduced and the formulation of homomorphic topological groups within such covering spaces is presented. Next, the topological properties of embeddings of such covering spaces in a fibered topological space are investigated in detail, involving finite as well as symmetric translations restricted on the identity-rigid fibers. It is shown that the embeddings give rise to two varieties of fibers and the path-homotopy equivalence is preserved by different topological structures within the embedded subspace. Moreover a discrete-loop variety of fundamental groups is generated within the embedded subspace under fibration.
The rest of the paper is organized as follows. The preliminary concepts are presented in Section 2 as a set of existing definitions and theorems. The definitions related to proposed topological structures are presented in Section 3. The main results are presented in Section 4. Finally, Section 5 concludes the paper.
2. Preliminary Concepts
In algebraic topology, the structure and properties of topological spaces are investigated by studying the behaviors of open as well as closed continuous functions within the space along with their continuous deformations. In this section, a set of classical as well as contemporary results are presented in relation to the covering spaces, fibrations, covering homotopy varieties and associated isomorphism of fundamental groups. Let two topological spaces be denoted as and such that where and . If we consider two continuous functions and then the continuity of is preserved if, and only if, the following conditions are satisfied.
The concept of covering space is central to the algebraic topology. An elementary neighborhood of a topological space is a subspace of which can be surjectively mapped under additional conditions leading to the concept of covering space. The definition of covering space and projection is presented as follows.
2.1. Definition: Covering Spaces
Let a continuous surjective function be given as where the topological space is called a base space. If it is true that , the function generates covers which are homeomorphically mapped onto , then the function is called a covering projection or covering map.
It is important to note that base subspace is considered to be path-connected topological subspace. If we consider on a complex plane then it results in the formulation of covering path theorem which is presented as follows [11,12].
Theorem 1.
If
is a path such that then there is a unique covering path
such that
.
The above theorem can be further generalized for any . Suppose a continuous function is defined as such that . If it is considered that then the corresponding unique covering path can also be formulated. The respective covering homotopy is a related concept which can be presented in the following theorem [11,13,14].
Theorem 2.
If the function
is a homotopy such that
then the function
is a covering homotopy where
.
Interestingly, the covering homotopy property needs a generalized reconstruction in the covering spaces by considering the uniqueness of a covering path. If there is a continuous function and in the corresponding covering space such that then the covering homotopy in a covering space can be established as presented in the following theorem [11].
Theorem 3.
If
is a covering space of topological base space
under surjection
and
is a homotopy with
then there is a covering homotopy in the covering space given by
such that
.
The fibration in a path-connected topological space can be defined in the respective covering spaces and in terms of homotopy lifting. Moreover, there exists a special variety of coverings called compact-covering in a metrizable space. Let us consider two continuous functions between two topological spaces which are denoted as . The definitions of fibration in covering space, compact-covering and point-countable cover are presented as follows.
2.2. Definitions: Fibration and Covering Varieties
Let be a lifting of and the function is a homotopy from to . There is a homotopy such that where is a covering projection [2]. First, we present the definition of covering fibration and its discrete variety in a covering space. The definitions of two different notions related to coverings are presented next.
Fibration [8,13]: A fibering of a topological covering space is a structure given by where is a covering projection from fibered , is a collection of open sets (i.e., the neighborhood components in base space), and is continuous. A corresponding G-covering space contains discrete fibers in the covering projection (i.e., the covering space is a discretely fibered space).
Compact-covering [15]: A function is called compact-covering if such that . It is important to note that the covering maps or covering projections preserve complete metrizability under certain conditions.
Point-countable cover [16]: Suppose is a cover of space and is a finite subcover. The space is defined as having a point-countable cover if where in .
The equivalence between multiple covering spaces and the corresponding multiple covering projections can be established in the presence of covering varieties. If two different covering projections are given as and then they are called equivalent if, and only if, there is a homeomorphism such that . This leads to the conjugacy theorem of fundamental groups in the covering spaces, as presented in the following theorem [11,13].
Theorem 4.
If
then
and
are conjugate to the fundamental group
.
Finally, if a covering projection is given then any two universal covering spaces of a base space are isomorphic to each other. Furthermore the path connectedness of a topological space preserves the isomorphisms of two fundamental groups and in the space.
3. Topological Structures and Definitions
Let a second countable Hausdorff as well as compact normal topological space be represented as such that and an open set contains the point where . Suppose where , is also a space such that and is a second countably compact space (i.e., a variety of compact Lindelof space). If is a topological subspace such that and is an open neighborhood of the point then the surjective function given by is a covering map of and represents the respective covering spaces. It is considered in this paper that the covering spaces are finite variety, and as a result is compact. Consequently, the covering spaces maintain the property that if where and each compact cover is a path-connected component. In this paper the i-th path-connected component of the covering spaces is denoted as such that . Note that the compactness of spaces and enables the formulation of locally homeomorphic embeddings into a non-compact space . In this paper, the topological embeddings are employed to construct the embedded subspaces, preserving local homeomorphism. It is important to note that the topological injective embeddings forming a Noetherian structure in covering spaces do not consider the group algebraic standpoints and such embeddings are completely topological in nature. The reason is that the set of finite groups in covering components in a topological space are distinct. The definitions of groups in covering spaces, the corresponding homeomorphic embeddings of subspaces and the concept of identity fiber are presented in Section 3.1, Section 3.2, Section 3.3 and Section 3.4. First we present the concept of compact Lindelof and Noetherian (LN) variety of covering spaces through the topological embeddings and the construction of a set of homeomorphic finite groups within such spaces. Note that in this paper all topological spaces are considered to be second-countable Hausdorff spaces in nature and the topological groups are compactible as well as connected.
3.1. Definition: LN Covering of (C, R) Space
Let be a compact topological space and the corresponding embedding within covering spaces generated by be given by the injective function such that condition is preserved. The covering space is defined to be an LN variety if whenever .
Note that the LN covering path components are finite and countable maintaining the property that . If we consider a topological space such that and the space is not compact then a set of suitable injective embeddings can be formulated maintaining local homeomorphisms.
3.2. Definition: Covering Space Embeddings
Let be a non-compact topological space where and are homeomorphic topological embeddings. The corresponding embeddings are called covering space embeddings if it preserve while maintaining as well as properties.
Remark 1.
It is important to note that the locally hoemomorphic embeddings retain the covering map as
such that
the injective and homeomorphic topological embedding maintains the property given by
. Moreover it is relatively straightforward to observe that
within the respective topological space.
Suppose the surjection is given as where . The finite LN covering of spaces can suitably admit a sequence of embeddings forming a Noetherian topological structure in given by where . This property assists to establish a set of finite group algebraic structures in which are embeddable, retaining the respective group homomorphism in . First, we define the topological group structures and group homomorphism in the covering spaces under topological embeddings.
3.3. Definition: Finite Covering Space Groups
Let be a countable set of finite (locally compactible as well as locally connected) topological groups such that where is a covering path component and is closed in where and . If the LN covering of spaces admits the property that such that and then are homeomorphic groups if, and only if, is a group homomorphism.
Remark 2.
Note that the structures of Noetherian covering spaces under topological embeddings should be maintained by . Hence, we are not restricting to the strictly bijective variety of and as result it is considered that
such that
maintaining generality, where
is the identity element. Note that
the homeomorphic embedding
is also a group in
. In addition, the locally homeomorphic embeddings maintain that
such that
preserving identity of
.
3.4. Definition: Identity Fiber and Rigidity
Let the two path components in covering spaces generated by be given as respectively. A compact fiber at is defined to be an identity fiber if, and only if, such that . An identity fiber is called as an identity-rigid variety if and conditions are maintained in and respectively.
Note that in general we consider that if and are two identity fibers then in . However, if the fiber in is identity-rigid then there exists a real projection such that and where is a finite linear projective translation with respect to the corresponding fiber with symmetry. Recall that the condition preserves the respective group structures due to local homeomorphisms in . Moreover if is compact identity-rigid then a corresponding compact identity-rigid fiber can be found in fibered maintaining the respective group homomorphism if, and only if, is path connected.
4. Main Results
A homeomorphic embedding of LN covering of space into a fibered space enables the formulation of the topological properties related to homotopy structures, where is a locally path-connected variety. It is important to observe that although the covering space is a locally path-connected variety, the corresponding embedded subspace in is a locally dense and completely path-connected variety maintaining local homeomorphisms of LN covering components.
Let a non-compact fiber in the topological space at be given as such that . According to definitions, the subspaces generated by in are a finite variety. Suppose a set of continuous functions are formulated as such that and . This results in the formation of a discrete variety of fundamental group in under homotopic path products, as presented in the following theorem.
Theorem 5.
If
is an LN covering space in fibered topological
space
then
is a discrete fundamental group where
and
.
Proof.
Let be a compact topological space and be a finite LN covering space. According to the locally homeomorphic embeddings into a fibered space , it follows that and is a covering space of such that . Suppose is a compact fiber such that and where and . Let a continuous function be considered such that and in the subspace . If we consider a set of continuous functions given by such that three conditions given by: (1) , (2) and (3) are maintained, then the following path-homotopy equivalence relation is attained.
Thus the set in preserves the path-homotopy equivalence relation in as follows.
Hence, the topological structure admits a discrete variety of fundamental group at the base point in the subspace . □
Remark 3.
It is important to note that the projections on the corresponding real subspaces denoted as
of the LN covering path components
in
should maintain the property that
and
retaining homeomorphism. Moreover, the following algebraic identities of path-homotopy are maintained by for
.
If we consider the existence of topological groups in the path-connected LN covering spaces (i.e., the covering spaces are in a dense topological subspace under embeddings), then the fiber-connected distributed groups exhibit interesting homotopy properties if two such topological groups maintain group homomorphism under the identity fiber. The following theorem presents this interesting observation.
Theorem 6.
If
, are two topological groups in the respective LN covering of
spaces and
is a homomorphism, then there exists a path-homotopy equivalence with respect to an identity fiber in the topological space .
Proof.
Let be two path-components of LN covering of spaces in such that . Suppose we consider an identity fiber in the respective topological space such that and . If , are two topological groups in maintaining the corresponding group homomorphism then such that . As the fiber is an identity fiber so it can be concluded that and maintaining generality. Suppose we consider a continuous function such that . Note that the covering space is a path-connected variety which allows us to formulate a continuous function such that where . Hence, by considering we can formulate a set of path-homotopy equivalences in which are given as: (1) and (2) . □
Note that the function maintains a path-homotopy equivalence at the base point which can be represented as . If we consider that is a dense and simply connected subspace then an arbitrary continuous function in the dense subspace also preserves the path-homotopy equivalence property. This observation is presented in the following lemma.
Lemma 1.
Let the covering space
be a simply connected locally dense subspace and the function
is continuous. If the function
is arbitrary such that
then the path-homotopy
is preserved with respect to the identity fiber
.
Proof.
The proof is relatively straightforward. If we consider that is a simply connected locally dense subspace then it is path-connected. Hence a continuous function can be constructed such that it maintains two conditions given as: and . Hence, a path-homotopy is formulated in which is given by where is a continuous function such that is preserved. □
Interestingly, there is interplay between the algebraic properties of group homomorphism in LN covering of spaces and the homotopy property if the space is a simply connected variety and the fiber is identity-rigid. Suppose the finite linear translation in the respective topological space is restricted on the fiber which is denoted as . We show in the following theorem that such translation establishes a path-homotopy equivalence on the identity-rigid fiber if .
Theorem 7.
If
and
are respective identities of
and such that
is identity-rigid then the continuous function
preserves the path-homotopy equivalence relation under finite translation
.
Proof.
Let be two LN covering components of space of a neighborhood where and . Suppose is a non-compact topological space such that . If we consider a compact identity-rigid fiber then we can conclude that where and are the identities of respective groups and . If the function is a group homomorphism then . If the continuous function is constructed such that then we can conclude that . Hence, if the finite linear translation on fiber maintains the property that then we can further conclude that in . □
Remark 4.
It is important to note that in this case
are considered to be simply connected topological subspaces such that
in
the continuous function
is nullhomotopic in nature where
is preserved. If we relax this condition then the aforesaid property may not always be satisfied if we enforce the condition that is also a fundamental group in
.
Interestingly, if a group in the LN covering of space is a trivial group then an equivalence relation involving the finite linear translation on an identity-rigid fiber can be established. This observation is presented in the following lemma.
Lemma 2.
If
is a trivial group then
such that
in
where the fiber is identity-rigid.
Proof.
Let in the topological space two topological groups be presented as and such that is a trivial group and in the corresponding LN covering of space . If there is a group homomorphism where then the function maintains the property given by . Moreover in this case condition is preserved by the trivial group . Suppose we consider a linear finite translation on the identity-rigid fiber in . Thus such that in where and . Hence we can conclude that and this results in the property given by . □
The formulation of path-homotopy equivalences on a single fiber requires the specific condition about the position of identity elements in a fibered topological space. However a more relaxed version of path-homotopy equivalences can be formulated involving multiple fibers in the topological space where the identity elements are distributed on multiple fibers for respective group structures within the embedded LN covering of space. This observation is presented in the following theorem.
Theorem 8.
If a fibered topological
space
is dense then
such that the continuous function
establishes path-homotopy equivalence where
and
on the respective identity fibers for finite topological groups
under locally homeomorphic embeddings in
.
Proof.
Let us consider that be a group homomorphism in the LN covering space . Suppose the space is locally dense and the finite variety of two topological groups and are established such that where . Suppose the group identities of two locally homeomorphic group embeddings are given as and for the respective . Let the two fibers in a dense topological space maintain the following conditions.
Note that the respective fibers are identity fibers in this case. Thus there exists a continuous function such that and in . Now consider another continuous function in given by such that . Note that the locally homeomorphic embeddings preserve group homomorphism as . Hence the continuous function in dense maintains a path-homotopy equivalence relation given by involving the corresponding two identity fibers . □
The locally homeomorphic embeddings of LN covering of spaces and the corresponding projections of fibers on a path component of covering spaces generate a cyclic group structure under certain conditions. First, the projections of fibers on real subspace need to be finite, and second the resulting planar subspace forms a 2-simplex. This interesting property is presented in the following theorem.
Theorem 9.
If
is a dense topological
space containing
then there exists a cyclic group structure under finite real projections of fibers into embedded LN covering spaces.
Proof.
Let be a dense topological space such that is the embedded LN covering spaces of corresponding such that . If is a fibered space then one can select three fibers such that , and where . Moreover if the respective projections on real subspace maintains the property that then we can infer that such that and . Thus a planar 2-simplex is formed in denoted as and a corresponding planar as well as closed triangulated topological subspace is generated which is given by . Hence a prime ordered cyclic group is formed where . □
Remark 5.
Note that the linear translations restricted to fibers given by
admits
as long as
where
. However the restriction to be maintained is that the finite fiber-restricted translations within the space must maintain symmetry condition given by
so that the cyclic group structure is preserved considering that
represents the identity element.
Corollary 1.
Even if the structure
is generated by
in
such that
and
then
forming
which preserves cyclic group structure successfully as
where the group operation is an abstract algebraic operation.
Proof.
The proof is straightforward if we consider that the finite real projection generates such that and the group operation is an abstract algebraic operation retaining the prime ordered cyclic group structure. □
Remark 6.
It is interesting to note that
is largely a relaxed variety because it does not require the topological condition that every continuous function is nullhomotopic in nature. However, in this case there is a restriction with respect to the translation of by employing any finite linear function
in order to retain the
structure for some
. Note that some forms of finite linear translations support
structure; however some other varieties of translations will not. This property is presented in the following theorem.
Theorem 10.
If
is a finite linear translation then
is a cyclic group if, and only if,
is simply connected.
Proof.
Let us consider a separation of topological subspace such that where and . Suppose we consider that and such that and . Now consider a continuous function in the subspace given by . If we impose two contradictory conditions on the restriction of the function within the separation such that is nullhomotopic and is not nullhomotopic then the finite linear translation function violates property and as result such a translation does not exist in supporting . Hence, the subspace is simply connected by the nullhomotopic function and as a result is also nullhomotopic in its separations preserving cyclic group structure under finite translations. □
Corollary 2.
If the fiber
is arbitrary (i.e., general fiber) such that
where
then the covering projection of fundamental group
maintains the property that
if, and only if, there is a continuous function
such that
.
The proof of aforesaid corollary is straightforward and it shows that a fibered topological space containing embedded LN covering spaces and base space successfully preserves the classification of covering spaces in terms of fundamental groups. In other words the interplay of homotopy and topological groups in a fibered topological covering space of LN variety with embeddings does not interfere with the classical results related to the covering space classifications based on fundamental groups.
5. Conclusions
The topological covering (C, R) spaces enable suitable incorporation of additional structures enhancing the richness of their properties. The compact Lindelof variety of path-connected components of covering (C, R) spaces enables the formulation of finite group algebraic structures within the spaces. The groups can be equipped with homomorphism and the corresponding finite Noetherian covering spaces formed by homeomorphic embeddings allowtable the formulation of various path-homotopy equivalences in the fibered topological (C, R) space. The interplay of finite homomorphic groups in the path-connected components of covering spaces and the topological fibers generates a discrete variety of fundamental group structure within the embedded dense subspaces. The topological fibers get classified into several varieties depending on the position of identity elements of the embedded homomorphic groups. As a result a wide array of path-homotopy equivalences is formulated within the embedded LN covering spaces including the base space. The rigidity of fibers based on identity and the multiplicity of fibers support path-homotopy equivalences considering that the path connected covering components are simply connected in view of nullhomotopy. Interestingly, the resulting 2-simplex structures and finite as well as symmetric translations within the fibered covering space assists in determining the simple connectedness of the path-connected covering components under topological embeddings.
Funding
The research is funded by Gyeongsang National University, Jinju, Korea.
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
Not applicable.
Acknowledgments
Author likes to thank anonymous reviewers and editors for their valuable comments and suggestions.
Conflicts of Interest
The author declares no conflict of interest.
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