Let M be a closed n-manifold of positive sectional curvature. Assume that M admits an effective isometrical T1× Zpk-action with p prime. The main result of the article n+1 for n 〉 5, then there exists a positiv...Let M be a closed n-manifold of positive sectional curvature. Assume that M admits an effective isometrical T1× Zpk-action with p prime. The main result of the article n+1 for n 〉 5, then there exists a positive constant p(n), is that ifk=lforn=3or k〉 n+1/4 for n≥5,then there exists a positive constant p(n),depending only on n, such that π1 (M) is cyclic if p ≥ p(n).展开更多
It is proved that there is no chaotic group actions on any topological space with free arc.In this paper the chaotic actions of the group like G×F ,where F is a finite group,are studied.In particular,under...It is proved that there is no chaotic group actions on any topological space with free arc.In this paper the chaotic actions of the group like G×F ,where F is a finite group,are studied.In particular,under a suitable assumption,if F is a cyclic group,then the topological space which admits a chaotic action of Z×F must admit a chaotic homeomorphism.A topological space which admits a chaotic group action but admits no chaotic homeomorphism is constructed.展开更多
In this paper,we present the concept of Banach-mean equicontinuity and prove that the Banach-,Weyl-and Besicovitch-mean equicontinuities of a dynamic system of Abelian group action are equivalent.Furthermore,we obtain...In this paper,we present the concept of Banach-mean equicontinuity and prove that the Banach-,Weyl-and Besicovitch-mean equicontinuities of a dynamic system of Abelian group action are equivalent.Furthermore,we obtain that the topological entropy of a transitive,almost Banach-mean equicontinuous dynamical system of Abelian group action is zero.As an application of our main result,we show that the topological entropy of the Banach-mean equicontinuous system under the action of an Abelian groups is zero.展开更多
In this paper,the entropy of discrete Heisenberg group actions is considered.Let α be a discrete Heisenberg group action on a compact metric space X.Two types of entropies,h and h(α)are introduced,in which h is defi...In this paper,the entropy of discrete Heisenberg group actions is considered.Let α be a discrete Heisenberg group action on a compact metric space X.Two types of entropies,h and h(α)are introduced,in which h is defined in Ruelle’s way and h(α) is defined via the natural extension of α.It is shown that when X is the torus and α is induced by integer matrices then h is zero and h(α) can be expressed via the eigenvalues of the matrices.展开更多
We study several stronger versions of sensitivity for minimal group actions,including nsensitivity,thick n-sensitivity and blockily thick n-sensitivity,and characterize them by the regionally proximal relation.
In this paper,we observe a special kind of continuous functions on graphs.By estimating the integrals of these functions,we prove that there are no sensitive commutative group actions on graphs.Furthermore,we consider...In this paper,we observe a special kind of continuous functions on graphs.By estimating the integrals of these functions,we prove that there are no sensitive commutative group actions on graphs.Furthermore,we consider a 1-dimensional continuum composed of a spiral curve and a circle and show that there exist sensitive homeomorphisms on it,which answers negatively a question proposed by Kato in 1993.展开更多
Analytic atlases on <img src="Edit_948e45b7-cbef-425e-bb79-28648b859994.png" width="23" height="22" alt="" /> can be easily defined making it an <em>n</em>-dim...Analytic atlases on <img src="Edit_948e45b7-cbef-425e-bb79-28648b859994.png" width="23" height="22" alt="" /> can be easily defined making it an <em>n</em>-dimensional complex manifold. Then with the help of bi-M<span style="white-space:nowrap;"><span style="white-space:nowrap;">ö</span></span>bius transformations in complex coordinates Abelian groups are constructed making this manifold a Lie group. Actions of Lie groups on differentiable manifolds are well known and serve different purposes. We have introduced in previous works actions of Lie groups on non orientable Klein surfaces. The purpose of this work is to extend those studies to non orientable <em>n</em>-dimensional complex manifolds. Such manifolds are obtained by factorizing <img src="Edit_7e5721ee-bb7f-4224-bd52-7d4641ac1c73.png" width="23" height="22" alt="" /> with the two elements group of a fixed point free antianalytic involution of <img src="Edit_ddfdac64-b296-48c5-9bb2-932eb3d76008.png" width="23" height="22" alt="" />. Involutions <strong>h(z)</strong> of this kind are obtained linearly by composing special M<span style="white-space:nowrap;"><span style="white-space:nowrap;">ö</span></span>bius transformations of the planes with the mapping <img src="Edit_4cda269a-9399-41ae-a5da-0c9d18a419ab.png" width="89" height="24" alt="" /><img src="Edit_4cda269a-9399-41ae-a5da-0c9d18a419ab.png" width="85" height="22" alt="" />. A convenient partition of <img src="Edit_9e899708-41b0-4351-a12b-cc6efb5b1581.png" width="23" height="22" alt="" /> is performed which helps defining an internal operation on <img src="Edit_7cd42987-68f8-4e4c-9382-cbc68b56377e.png" width="49" height="26" alt="" /> and finally actions of the previously defined Lie groups on the non orientable manifold <img src="Edit_5740b48c-f9ea-438d-a87d-8cdc1f83662b.png" width="49" height="25" alt="" /> are displayed.展开更多
The Ribaucour transformations for flat Lagrangian submanifolds in Cn and CPn via loop group actions are given. As a consequence, the authors obtain a family of new flat Lagrangian submanifolds from a given one via a p...The Ribaucour transformations for flat Lagrangian submanifolds in Cn and CPn via loop group actions are given. As a consequence, the authors obtain a family of new flat Lagrangian submanifolds from a given one via a purely algebraic algorithm. At the same time, it is shown that such Ribaucour transformation always comes with a permutability formula.展开更多
In this paper we present systematic differential representations for the dynamical group SO(4).Theserepresentations include the left and the right differential representations and the left and the right adjoint differ...In this paper we present systematic differential representations for the dynamical group SO(4).Theserepresentations include the left and the right differential representations and the left and the right adjoint differentialrepresentations in both the group parameter space and its coset spaces.They are the generalization of the differentialrepresentations of the SO(3) rotation group in the Euler angles.These representations may find their applications in thestudy of the physical systems with SO(4) dynamical symmetry.展开更多
This paper determines the group structure of stabilizer of 2×2 matrix under similarity action over arbitrary field. Then, the cardinal number of any orbit is calculated over finite field.
In this article, we introduce the notion of fuzzy G-module by defining the group action of G on a fuzzy set of a Z-module M. We establish the cases in which fuzzy submodules also become fuzzy G-submodules. Notions of ...In this article, we introduce the notion of fuzzy G-module by defining the group action of G on a fuzzy set of a Z-module M. We establish the cases in which fuzzy submodules also become fuzzy G-submodules. Notions of a fuzzy prime submodule, fuzzy prime G-submodule, fuzzy semi prime submodule, fuzzy G-semi prime submodule, G-invariant fuzzy submodule and G-invariant fuzzy prime submodule of M are introduced and their properties are described. The homomorphic image and pre-image of fuzzy G-submodules, G-invariant fuzzy submodules and G-invariant fuzzy prime submodules of M are also established.展开更多
In this paper, the group action of a local wild Bocs'rep. category is introduced. And, it computed the parametric numbers U(n) and P(n) of the rep. category mod n(A) and ind n(t) in case n=1,2 with geometric met...In this paper, the group action of a local wild Bocs'rep. category is introduced. And, it computed the parametric numbers U(n) and P(n) of the rep. category mod n(A) and ind n(t) in case n=1,2 with geometric method.展开更多
Segal’s chronometric theory is based on a space-time D, which might be viewed as a Lie group with a causal structure defined by an invariant Lorentzian form on the Lie algebra u(2). Similarly, the space-time F is rea...Segal’s chronometric theory is based on a space-time D, which might be viewed as a Lie group with a causal structure defined by an invariant Lorentzian form on the Lie algebra u(2). Similarly, the space-time F is realized as the Lie group with a causal structure defined by an invariant Lorentzian form on u(1,1). Two Lie groups G, GF are introduced as representations of SU(2,2): they are related via conjugation by a certain matrix Win Gl(4). The linear-fractional action of G on D is well-known to be global, conformal, and it plays a crucial role in the analysis on space-time bundles carried out by Paneitz and Segal in the 1980’s. This analysis was based on the parallelizing group U(2). In the paper, singularities’ general (“geometric”) description of the linear-fractional conformal GF-action on F is given and specific examples are presented. The results call for the analysis of space-time bundles based on U(1,1) as the parallelizing group. Certain key stages of such an analysis are suggested.展开更多
The Lima call for climate action adopted at the Lima Climate Conference on Climate Change specifies that the principles of the United Nations Framework Convention on Climate Change,including the principle of common bu...The Lima call for climate action adopted at the Lima Climate Conference on Climate Change specifies that the principles of the United Nations Framework Convention on Climate Change,including the principle of common but differentiated responsibilities,shall apply to the new climate agreement to be adopted at the Paris Conference on Climate Change in 2015.Decisions on other heavily debated items,including the intended nationally determined contributions,were also made at the Lima Conference.The significant achievements in Lima and the positive momentum have laid a solid foundation for the adoption of a new climate agreement in the Paris Climate Conference.Four measures are proposed for China to meet great challenges in addressing climate change beyond 2020,including early formulation and issuance of a climate change law,establishment of a greenhouse gas emission trading scheme,promotion of advanced climate technology investments,and further international engagement for climate change.展开更多
We study the Bredon-IUman cohomology with local coefficients for a G-space X in the case of G being a totally disconnected, locally compact group. We prove that any short exact sequence of equivariant local coefficien...We study the Bredon-IUman cohomology with local coefficients for a G-space X in the case of G being a totally disconnected, locally compact group. We prove that any short exact sequence of equivariant local coefficients systems on X gives a long exact sequence of the associated Bredon-Illman cohomology groups with local coefficients.展开更多
Investments in bio-energies require deep and accurate analysis to evaluate their economical feasibility both by the investors' and the policy makers' perspectives. The chance to attain locally organized supply chain...Investments in bio-energies require deep and accurate analysis to evaluate their economical feasibility both by the investors' and the policy makers' perspectives. The chance to attain locally organized supply chains is presumably higher where there is a higher concentration of human, natural and financial capitals. After a literature review about social capital and energy supply chain (prg. 1), we investigate the instruments for public direct financial incentive (prg. 2) and the development of the public intervention plans in the agro-energy sector within the Local Development Plans (LDP) by Local Action Groups (LAG). Then, we present the case study of the Apulia Region (prg. 3) based upon a unique dataset, specifically built that collects LDP data relative to social capital. We finally propose a new methodological approach that makes use of social network analysis investigating the net of relationships underneath the territorial organization of the LAGs and the local supply chains. Results seem to show that site specificities affect the sustainability of biofuels supply chains, and that effect seems to be reciprocally bounded, thus calling for the inclusion of such measures when planning new policies, and for analytical approaches encompassing historical perspectives. Finally, we draw the conclusions.展开更多
The author studies the relation of continuous-trace property between C*-algebra A and the fixed point C*-algebra Aα in certain C*-dynamic system (A, G, α) by introducing an α-invariant continuous trace property. F...The author studies the relation of continuous-trace property between C*-algebra A and the fixed point C*-algebra Aα in certain C*-dynamic system (A, G, α) by introducing an α-invariant continuous trace property. For separable C*-dynamic system (A, G, α) with G compact and abelian,A liminal, αt ∈ AutCb(A) (A) and pointwise unitary, the necessary and sufficient condition for A to be continuous-trace, which contains Aα continuousitrace, is obtained.展开更多
In this paper, we present a new form of “special relativity” (BSR), which is isomorphic to Einstein’s “special relativity” (ESR). This in turn proves the non-uniqueness of Einstein’s “special relativity” and i...In this paper, we present a new form of “special relativity” (BSR), which is isomorphic to Einstein’s “special relativity” (ESR). This in turn proves the non-uniqueness of Einstein’s “special relativity” and implies the inconclusiveness of so-called “relativistic physics”. This work presents new results of principal significance for the foundations of physics and practical results for high energy physics, deep space astrophysics, and cosmology as well. The entire exposition is done within the formalism of the Lorentz <em>SL</em>(2<em>C</em>) group acting via isometries on <strong>real 3-dimensional Lobachevskian (hyperbolic) spaces</strong> <em>L</em><sup>3</sup> regarded as quotients <span style="white-space:nowrap;"><em>SL</em>(2<em>C</em>)/<em>SU</em>(2)</span>. We show via direct calculations that both ESR and BSR are parametric maps from Lobachevskian into Euclidean space, namely a <strong>gnomonic</strong> (central) map in the case of ESR, and a<strong> stereographic </strong>map in the case of BSR. Such an identification allows us to link these maps to relevant models of Lobachevskian geometry. Thus, we identify ESR as the physical realization of the Beltrami-Klein (non-conformal) model, and BSR as the physical realization of the Poincare (conformal) model of Lobachevskian geometry. Although we focus our discussion on ball models of Lobachevskian geometry, our method is quite general, and for instance, may be applied to the half-space model of Lobachevskian geometry with appropriate “Lorentz group” acting via isometries on (positive) half space, resulting yet in another “special relativity” isomorphic with ESR and BSR. By using the notion of a<strong> homotopy</strong> of maps, the identification of “special relativities” as maps from Lobachevskian into Euclidean space allows us to justify the existence of an uncountable infinity of hybrid “special relativities” and consequently an uncountable infinity of “relativistic physics” built upon them. This is another new result in physics and it states that so called “relativistic physics” is unique only up to a homotopy. Finally, we show that “paradoxes” of “special relativities” in either ESR or BSR are simply common distortions of maps between non-isometric spaces. The entire exposition is kept at elementary level accessible to majority of students in physics and/or engineering.展开更多
文摘Let M be a closed n-manifold of positive sectional curvature. Assume that M admits an effective isometrical T1× Zpk-action with p prime. The main result of the article n+1 for n 〉 5, then there exists a positive constant p(n), is that ifk=lforn=3or k〉 n+1/4 for n≥5,then there exists a positive constant p(n),depending only on n, such that π1 (M) is cyclic if p ≥ p(n).
文摘It is proved that there is no chaotic group actions on any topological space with free arc.In this paper the chaotic actions of the group like G×F ,where F is a finite group,are studied.In particular,under a suitable assumption,if F is a cyclic group,then the topological space which admits a chaotic action of Z×F must admit a chaotic homeomorphism.A topological space which admits a chaotic group action but admits no chaotic homeomorphism is constructed.
基金supported by NSF of China(11671057)NSF of Chongqing(cstc2020jcyj-msxmX0694)the Fundamental Research Funds for the Central Universities(2018CDQYST0023).
文摘In this paper,we present the concept of Banach-mean equicontinuity and prove that the Banach-,Weyl-and Besicovitch-mean equicontinuities of a dynamic system of Abelian group action are equivalent.Furthermore,we obtain that the topological entropy of a transitive,almost Banach-mean equicontinuous dynamical system of Abelian group action is zero.As an application of our main result,we show that the topological entropy of the Banach-mean equicontinuous system under the action of an Abelian groups is zero.
基金Supported by NSFC (Grant Nos. 12171400, 12126102)。
文摘In this paper,the entropy of discrete Heisenberg group actions is considered.Let α be a discrete Heisenberg group action on a compact metric space X.Two types of entropies,h and h(α)are introduced,in which h is defined in Ruelle’s way and h(α) is defined via the natural extension of α.It is shown that when X is the torus and α is induced by integer matrices then h is zero and h(α) can be expressed via the eigenvalues of the matrices.
基金Supported by NNSF of China(Grant Nos.11771264,11871188)NSF of Guangdong Province(Grant No.2018B030306024)。
文摘We study several stronger versions of sensitivity for minimal group actions,including nsensitivity,thick n-sensitivity and blockily thick n-sensitivity,and characterize them by the regionally proximal relation.
基金the Special Foundation of National Prior Basic Researches of China(Grant No.G1999075108)partially supported by the National Natural Science Foundation of China(Grant No.10501042)
文摘In this paper,we observe a special kind of continuous functions on graphs.By estimating the integrals of these functions,we prove that there are no sensitive commutative group actions on graphs.Furthermore,we consider a 1-dimensional continuum composed of a spiral curve and a circle and show that there exist sensitive homeomorphisms on it,which answers negatively a question proposed by Kato in 1993.
文摘Analytic atlases on <img src="Edit_948e45b7-cbef-425e-bb79-28648b859994.png" width="23" height="22" alt="" /> can be easily defined making it an <em>n</em>-dimensional complex manifold. Then with the help of bi-M<span style="white-space:nowrap;"><span style="white-space:nowrap;">ö</span></span>bius transformations in complex coordinates Abelian groups are constructed making this manifold a Lie group. Actions of Lie groups on differentiable manifolds are well known and serve different purposes. We have introduced in previous works actions of Lie groups on non orientable Klein surfaces. The purpose of this work is to extend those studies to non orientable <em>n</em>-dimensional complex manifolds. Such manifolds are obtained by factorizing <img src="Edit_7e5721ee-bb7f-4224-bd52-7d4641ac1c73.png" width="23" height="22" alt="" /> with the two elements group of a fixed point free antianalytic involution of <img src="Edit_ddfdac64-b296-48c5-9bb2-932eb3d76008.png" width="23" height="22" alt="" />. Involutions <strong>h(z)</strong> of this kind are obtained linearly by composing special M<span style="white-space:nowrap;"><span style="white-space:nowrap;">ö</span></span>bius transformations of the planes with the mapping <img src="Edit_4cda269a-9399-41ae-a5da-0c9d18a419ab.png" width="89" height="24" alt="" /><img src="Edit_4cda269a-9399-41ae-a5da-0c9d18a419ab.png" width="85" height="22" alt="" />. A convenient partition of <img src="Edit_9e899708-41b0-4351-a12b-cc6efb5b1581.png" width="23" height="22" alt="" /> is performed which helps defining an internal operation on <img src="Edit_7cd42987-68f8-4e4c-9382-cbc68b56377e.png" width="49" height="26" alt="" /> and finally actions of the previously defined Lie groups on the non orientable manifold <img src="Edit_5740b48c-f9ea-438d-a87d-8cdc1f83662b.png" width="49" height="25" alt="" /> are displayed.
基金Supported by National Natural Science Foundation of China (Grant Nos. 10801103, 10801126 and 10871142)Natural Sciences Fund for Colleges and Universities in Jiangsu Province (Grant No. 08KJB110010)
文摘In this paper, using the integral method observed by Mai Jiehua recently, we show that no dendrite admits a sensitive commutative group action.
基金Project supported by the National Natural Science Foundation of China (No.10271106)the Education Commission of Zhejiang Province of China (No.20030342).
文摘The Ribaucour transformations for flat Lagrangian submanifolds in Cn and CPn via loop group actions are given. As a consequence, the authors obtain a family of new flat Lagrangian submanifolds from a given one via a purely algebraic algorithm. At the same time, it is shown that such Ribaucour transformation always comes with a permutability formula.
基金National Natural Science Foundation of China under Grant Nos.10205007,10226033,10375039,and 90503008the Nuclear Theory Research Program for NCET and Fund of HIRFL of China
文摘In this paper we present systematic differential representations for the dynamical group SO(4).Theserepresentations include the left and the right differential representations and the left and the right adjoint differentialrepresentations in both the group parameter space and its coset spaces.They are the generalization of the differentialrepresentations of the SO(3) rotation group in the Euler angles.These representations may find their applications in thestudy of the physical systems with SO(4) dynamical symmetry.
文摘This paper determines the group structure of stabilizer of 2×2 matrix under similarity action over arbitrary field. Then, the cardinal number of any orbit is calculated over finite field.
文摘In this article, we introduce the notion of fuzzy G-module by defining the group action of G on a fuzzy set of a Z-module M. We establish the cases in which fuzzy submodules also become fuzzy G-submodules. Notions of a fuzzy prime submodule, fuzzy prime G-submodule, fuzzy semi prime submodule, fuzzy G-semi prime submodule, G-invariant fuzzy submodule and G-invariant fuzzy prime submodule of M are introduced and their properties are described. The homomorphic image and pre-image of fuzzy G-submodules, G-invariant fuzzy submodules and G-invariant fuzzy prime submodules of M are also established.
文摘In this paper, the group action of a local wild Bocs'rep. category is introduced. And, it computed the parametric numbers U(n) and P(n) of the rep. category mod n(A) and ind n(t) in case n=1,2 with geometric method.
文摘Segal’s chronometric theory is based on a space-time D, which might be viewed as a Lie group with a causal structure defined by an invariant Lorentzian form on the Lie algebra u(2). Similarly, the space-time F is realized as the Lie group with a causal structure defined by an invariant Lorentzian form on u(1,1). Two Lie groups G, GF are introduced as representations of SU(2,2): they are related via conjugation by a certain matrix Win Gl(4). The linear-fractional action of G on D is well-known to be global, conformal, and it plays a crucial role in the analysis on space-time bundles carried out by Paneitz and Segal in the 1980’s. This analysis was based on the parallelizing group U(2). In the paper, singularities’ general (“geometric”) description of the linear-fractional conformal GF-action on F is given and specific examples are presented. The results call for the analysis of space-time bundles based on U(1,1) as the parallelizing group. Certain key stages of such an analysis are suggested.
文摘The Lima call for climate action adopted at the Lima Climate Conference on Climate Change specifies that the principles of the United Nations Framework Convention on Climate Change,including the principle of common but differentiated responsibilities,shall apply to the new climate agreement to be adopted at the Paris Conference on Climate Change in 2015.Decisions on other heavily debated items,including the intended nationally determined contributions,were also made at the Lima Conference.The significant achievements in Lima and the positive momentum have laid a solid foundation for the adoption of a new climate agreement in the Paris Climate Conference.Four measures are proposed for China to meet great challenges in addressing climate change beyond 2020,including early formulation and issuance of a climate change law,establishment of a greenhouse gas emission trading scheme,promotion of advanced climate technology investments,and further international engagement for climate change.
基金Acknowledgements This work was supported by the Foundation of Shanxi Scholarship Council of China (2011-024), the Foundation of Shanxi Province for Selected Returned Overseas Scholars, and the Natural Science Foundation of Shanxi Province (2013011001-2).
文摘We study the Bredon-IUman cohomology with local coefficients for a G-space X in the case of G being a totally disconnected, locally compact group. We prove that any short exact sequence of equivariant local coefficients systems on X gives a long exact sequence of the associated Bredon-Illman cohomology groups with local coefficients.
文摘Investments in bio-energies require deep and accurate analysis to evaluate their economical feasibility both by the investors' and the policy makers' perspectives. The chance to attain locally organized supply chains is presumably higher where there is a higher concentration of human, natural and financial capitals. After a literature review about social capital and energy supply chain (prg. 1), we investigate the instruments for public direct financial incentive (prg. 2) and the development of the public intervention plans in the agro-energy sector within the Local Development Plans (LDP) by Local Action Groups (LAG). Then, we present the case study of the Apulia Region (prg. 3) based upon a unique dataset, specifically built that collects LDP data relative to social capital. We finally propose a new methodological approach that makes use of social network analysis investigating the net of relationships underneath the territorial organization of the LAGs and the local supply chains. Results seem to show that site specificities affect the sustainability of biofuels supply chains, and that effect seems to be reciprocally bounded, thus calling for the inclusion of such measures when planning new policies, and for analytical approaches encompassing historical perspectives. Finally, we draw the conclusions.
文摘The author studies the relation of continuous-trace property between C*-algebra A and the fixed point C*-algebra Aα in certain C*-dynamic system (A, G, α) by introducing an α-invariant continuous trace property. For separable C*-dynamic system (A, G, α) with G compact and abelian,A liminal, αt ∈ AutCb(A) (A) and pointwise unitary, the necessary and sufficient condition for A to be continuous-trace, which contains Aα continuousitrace, is obtained.
文摘In this paper, we present a new form of “special relativity” (BSR), which is isomorphic to Einstein’s “special relativity” (ESR). This in turn proves the non-uniqueness of Einstein’s “special relativity” and implies the inconclusiveness of so-called “relativistic physics”. This work presents new results of principal significance for the foundations of physics and practical results for high energy physics, deep space astrophysics, and cosmology as well. The entire exposition is done within the formalism of the Lorentz <em>SL</em>(2<em>C</em>) group acting via isometries on <strong>real 3-dimensional Lobachevskian (hyperbolic) spaces</strong> <em>L</em><sup>3</sup> regarded as quotients <span style="white-space:nowrap;"><em>SL</em>(2<em>C</em>)/<em>SU</em>(2)</span>. We show via direct calculations that both ESR and BSR are parametric maps from Lobachevskian into Euclidean space, namely a <strong>gnomonic</strong> (central) map in the case of ESR, and a<strong> stereographic </strong>map in the case of BSR. Such an identification allows us to link these maps to relevant models of Lobachevskian geometry. Thus, we identify ESR as the physical realization of the Beltrami-Klein (non-conformal) model, and BSR as the physical realization of the Poincare (conformal) model of Lobachevskian geometry. Although we focus our discussion on ball models of Lobachevskian geometry, our method is quite general, and for instance, may be applied to the half-space model of Lobachevskian geometry with appropriate “Lorentz group” acting via isometries on (positive) half space, resulting yet in another “special relativity” isomorphic with ESR and BSR. By using the notion of a<strong> homotopy</strong> of maps, the identification of “special relativities” as maps from Lobachevskian into Euclidean space allows us to justify the existence of an uncountable infinity of hybrid “special relativities” and consequently an uncountable infinity of “relativistic physics” built upon them. This is another new result in physics and it states that so called “relativistic physics” is unique only up to a homotopy. Finally, we show that “paradoxes” of “special relativities” in either ESR or BSR are simply common distortions of maps between non-isometric spaces. The entire exposition is kept at elementary level accessible to majority of students in physics and/or engineering.