Institute of Mathematics AS CR, v. v. i.
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    On the differential geometry of some classes of infinite dimensional manifolds

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    summary:Albeverio, Kondratiev, and Röckner have introduced a type of differential geometry, which we call lifted geometry, for the configuration space ΓX\Gamma _X of any manifold XX. The name comes from the fact that various elements of the geometry of ΓX\Gamma _X are constructed via lifting of the corresponding elements of the geometry of XX. In this note, we construct a general algebraic framework for lifted geometry which can be applied to various “infinite dimensional spaces” associated to XX. In order to define a lifted geometry for a “space”, one dose not need any topology or local coordinate system on the space. As example and application, lifted geometry for spaces of Radon measures on XX, mappings into XX, embedded submanifolds of XX, and tilings on XX, are considered. The gradient operator in the lifted geometry of Radon measures is considered. Also, the construction of a natural Dirichlet form associated to a random measure is discussed. It is shown that Stokes’ Theorem appears as “differentiability” of “boundary operator” in the lifted geometry of spaces of submanifolds. It is shown that (generalized) action functionals associated with Lagrangian densities on XX form the algebra of smooth functions in a specific lifted geometry for the path-space of XX

    Some properties of generalized distance eigenvalues of graphs

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    summary:Let GG be a simple connected graph with vertex set V(G)={v1,v2,,vn}V(G)=\{v_1,v_2,\dots ,v_n \} and edge set E(G)E(G), and let dvid_{v_{i}} be the degree of the vertex viv_i. Let D(G)D(G) be the distance matrix and let Tr(G)T_r(G) be the diagonal matrix of the vertex transmissions of GG. The generalized distance matrix of GG is defined as Dα(G)=αTr(G)+(1α)D(G)D_\alpha (G)=\alpha T_r(G)+(1-\alpha )D(G), where 0α10\leq \alpha \leq 1. Let λ1(Dα(G))λ2(Dα(G))λn(Dα(G))\lambda _1(D_{\alpha }(G))\geq \lambda _2(D_{\alpha }(G)) \geq \ldots \geq \lambda _n(D_{\alpha }(G)) be the generalized distance eigenvalues of GG, and let kk be an integer with 1kn1\leq k\leq n. We denote by Sk(Dα(G))=λ1(Dα(G))+λ2(Dα(G))++λk(Dα(G))S_{k}(D_{\alpha }(G))=\lambda _{1}(D_{\alpha }(G)) +\lambda _{2}(D_{\alpha }(G))+\ldots +\lambda _{k}(D_{\alpha }(G)) the sum of the kk largest generalized distance eigenvalues. The generalized distance spread of a graph GG is defined as DαS(G)=λ1(Dα(G))λn(Dα(G))D_{\alpha }S(G)=\lambda _{1}(D_{\alpha }(G))-\lambda _{n}(D_{\alpha }(G)). We obtain some bounds on Sk((Dα(G)))S_k((D_{\alpha }(G))) and DαS(G)D_{\alpha }S(G) of graph GG, respectively

    Parametric representations of BiHom-Hopf algebras

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    summary:The main purpose of the present paper is to study representations of BiHom-Hopf algebras. We first introduce the notion of BiHom-Hopf algebras, and then discuss BiHom-type modules, Yetter-Dinfeld modules and Drinfeld doubles with parameters. We get some new nn-monoidal categories via the category of BiHom-(co)modules and the category of BiHom-Yetter-Drinfeld modules. Finally, we obtain a center construction type theorem on BiHom-Hopf algebras

    Global solvability in the parabolic-elliptic chemotaxis system with singular sensitivity and logistic source

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    summary:We study the chemotaxis system with singular sensitivity and logistic-type source: ut=Δuχ(uv/v)+ruμuku_t=\Delta u-\chi \nabla \cdot (u \nabla v/ v) +ru-\mu u^k, 0=Δvv+u0=\Delta v-v+u under the non-flux boundary conditions in a smooth bounded domain ΩRn\Omega \subset \mathbb {R}^n, χ,r,μ>0\chi ,r,\mu >0, k>1k>1 and n1n\ge 1. It is shown with k(1,2)k\in (1,2) that the system possesses a global generalized solution for n2n\ge 2 which is bounded when χ>0\chi >0 is suitably small related to r>0r>0 and the initial datum is properly small, and a global bounded classical solution for n=1n=1

    The clean elements of the ring R(L)\mathcal R(L)

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    summary:We characterize clean elements of R(L)\mathcal R(L) and show that αR(L)\alpha \in \mathcal {R}(L) is clean if and only if there exists a clopen sublocale UU in LL such that cL(coz(α1))UoL(coz(α))\frak {c}_L({\rm coz} (\alpha - {\bf 1})) \subseteq U \subseteq \frak {o}_L( {\rm coz} (\alpha )). Also, we prove that R(L)\mathcal R(L) is clean if and only if R(L)\mathcal R(L) has a clean prime ideal. Then, according to the results about R(L),\mathcal R(L), we immediately get results about $\mathcal C_{c}(L).

    Green-Liouville approximation and correct solvability in Lp(R)L_p(\mathbb R) of the general Sturm-Liouville equation

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    summary:We consider the equation (r(x)y(x))+q(x)y(x)=f(x),xR, -(r(x) y'(x))'+q(x)y(x)=f(x),\quad x\in \mathbb R, where fLp(R)f\in L_p(\mathbb R), p(1,)p\in (1,\infty ) and r>0,1rL1loc(R),qL1loc(R). r>0,\quad \frac {1}{r}\in L_1^{\rm loc}(\mathbb R),\quad q\in L_1^{\rm loc}(\mathbb R). For particular equations of this form, we suggest some methods for the study of the question on requirements to the functions rr and qq under which the above equation is correctly solvable in the space Lp(R),L_p(\mathbb R), $p\in (1,\infty ).

    Polyanalytic Besov spaces and approximation by dilatations

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    summary:Using partial derivatives f/z\partial f / \partial z and f/zˉ\partial f / \partial \bar {z}, we introduce Besov spaces of polyanalytic functions in the open unit disk, as well as in the upper half-plane. We then prove that the dilatations of functions in certain weighted polyanalytic Besov spaces converge to the same functions in norm. When restricted to the open unit disk, we prove that each polyanalytic function of degree qq can be approximated in norm by polyanalytic polynomials of degree at most qq

    The Plato–Galileo Problem

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    summary:Edice Fontes Scientiae zpřístupnila významná díla novověké vědy. Jde o soubor pěti knih obsahujících autentické a komentované překlady z děl evropské vědy 17. století. V článku je věnována zvláštní pozornost dopisům Isaaca Newtona, v nichž odpovídá na kosmologické otázky teologa Richarda Bentleyho. Všímáme si nastolené otázky, zda Newtonova fyzika umožňuje vysvětlení souvislosti oběžných rychlostí a poloměrů drah planet, což je úloha, kterou se zabýval i Galilei na základě Platónova popisu vzniku světa. Ptáme se, zda by Galileova hypotéza mohla platit při odlišné podobě gravitačního zákona a mohla tak v "alternativní historii" dovést Galilea k návrhu jeho matematického vyjádření

    News and Announcements

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    summary:Vzpomínka na profesora Martina Černohorského

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    Institute of Mathematics AS CR, v. v. i.
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