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Victor Buchstaber

Publications and source records attributed to Victor Buchstaber.

32 records · Page 2Linked to original sources
arXiv2018

Embeddings of moment-angle manifolds and sequences of Massey products

We show that for any face $F$ of a simple polytope $P$ the canonical equivariant homeomorphisms $h_P:\,\mathcal Z_P\to\mathcal Z_{K_P}$ and $h_F:\,\mathcal Z_F\to\mathcal Z_{K_F}$ are linked in a pentagonal commutative diagram with the maps of moment-angle manifolds and moment-angle-complexes, induced by a face embedding $i_{F,P}:\,F\to P$ and a simplicial embedding $Φ_{F,P}:\,K_F\to K_{F,P}\to K_P$, where $K_{F,P}$ is the full subcomplex of $K_P$ on the same vertex set as $Φ_{F,P}(K_F)$. We introduce the explicit constructions of the maps $i_{F,P}$, $Φ_{F,P}$ and show that a polytope $P$ is flag if and only if the induced embedding $\hat{i}_{F,P}:\,\mathcal Z_{F}\to\mathcal Z_P$ of moment-angle manifolds has a retraction and thus induces a split ring epimorphism in cohomology for any face $F\subset P$. As the applications of these results we obtain the sequences $\{P^n\}$ of flag simple polytopes such that there exists a nontrivial $k$-fold Massey product in $H^*(\mathcal Z_{P^n})$ with $k\to\infty$ as $n\to\infty$ and, moreover, the existence of a nontrivial $k$-fold Massey product in $H^*(\mathcal Z_{P^n})$ implies existence of a nontrivial $k$-fold Massey product in $H^*(\mathcal Z_{P^l})$ for any $l>n$.

math.AT↗
arXiv2018

Total positivity, Grassmannian and modified Bessel functions

A rectangular matrix is called totally positive, if all its minors are positive. A point of a real Grassmanian manifold $G_{l,m}$ of $l$-dimensional subspaces in $\mathbb R^m$ is called strictly totally positive, if one can normalize its Plücker coordinates to make all of them positive. The totally positive matrices and the subsets of strictly totally positive points in Grassmanian manifolds arise in many domains of mathematics, mechanics and physics. F.R.Gantmacher and M.G.Krein considered totally positive matrices in the context of classical mechanics. Total positivity was used for construction of solutions of the Kadomtsev-Petviashvili (KP) partial differential equation by T.M.Malanyuk, M.Boiti, F.Pemperini, A.Pogrebkov, Y.Kodama, L.Williams. Different problems of mathematics, mechanics and physics led to constructions of totally positive matrices due to many mathematicians, including F.R. Gantmacher, M.G.Krein, I.J.Schoenberg, S.Karlin, A.E.Postnikov and ourselves. In our case totally positive matrices were constructed for solution of problems on model of the overdamped Josephson effect in superconductivity and double confluent Heun equations. In our previous paper we have proved that certain determinants formed by modified Bessel functions of the first kind are positive on the positive semi-axis. In the present paper we give a new result: a construction of multidimensional families of totally positive matrices formed by values of modified Bessel functions with non-negative integer indices. Their columns are numerated by the indices of the modified Bessel functions, and their rows are numerated by their arguments.

math.DS↗
arXiv2018

Manifolds of isospectral arrow matrices

An arrow matrix is a matrix with zeroes outside the main diagonal, first row, and first column. We consider the space $M_{St_n,λ}$ of Hermitian arrow $(n+1)\times (n+1)$-matrices with fixed simple spectrum $λ$. We prove that this space is a smooth $2n$-manifold, and its smooth structure is independent on the spectrum. Next, this manifold carries the locally standard torus action: we describe the topology and combinatorics of its orbit space. If $n\geqslant 3$, the orbit space $M_{St_n,λ}/T^n$ is not a polytope, hence this manifold is not quasitoric. However, there is a natural permutation action on $M_{St_n,λ}$ which induces the combined action of a semidirect product $T^n\rtimesΣ_n$. The orbit space of this large action is a simple polytope. The structure of this polytope is described in the paper. In case $n=3$, the space $M_{St_3,λ}/T^3$ is a solid torus with boundary subdivided into hexagons in a regular way. This description allows to compute the cohomology ring and equivariant cohomology ring of the 6-dimensional manifold $M_{St_3,λ}$ using the general theory developed by the first author. This theory is also applied to a certain $6$-dimensional manifold called the twin of $M_{St_3,λ}$. The twin carries a half-dimensional torus action and has nontrivial tangent and normal bundles.

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arXiv2017

Cohomological rigidity of manifolds defined by right-angled 3-dimensional polytopes

A family of closed manifolds is called cohomologically rigid if a cohomology ring isomorphism implies a diffeomorphism for any two manifolds in the family. We establish cohomological rigidity for large families of 3-dimensional and 6-dimensional manifolds defined by 3-dimensional polytopes. We consider the class P of 3-dimensional combinatorial simple polytopes, different from a tetrahedron, whose facets do not form 3- and 4-belts. This class includes mathematical fullerenes, i.e. simple 3-polytopes with only 5-gonal and 6-gonal facets. By a theorem of Pogorelov, any polytope from P admits a right-angled realisation in Lobachevsky 3-space, which is unique up to isometry. Our families of smooth manifolds are associated with polytopes from the class P. The first family consists of 3-dimensional small covers of polytopes from P, or hyperbolic 3-manifolds of Loebell type. The second family consists of 6-dimensional quasitoric manifolds over polytopes from P. Our main result is that both families are cohomologically rigid, i.e. two manifolds M and M' from either of the families are diffeomorphic if and only if their cohomology rings are isomorphic. We also prove that if M and M' are diffeomorphic, then their corresponding polytopes are combinatorially equivalent. These results are intertwined with the classical subjects of geometry and topology, such as combinatorics of 3-polytopes, the Four Colour Theorem, aspherical manifolds, diffeomorphism classification of 6-manifolds and invariance of Pontryagin classes. The proofs use techniques of toric topology.

math.AT↗
arXiv2017

On manifolds defined by 4-colourings of simple 3-polytopes

Let $\mathcal{P}$ be the class of combinatorial 3-dimensional simple polytopes $P$, different from a tetrahedron, without 3- and 4-belts of facets. By the results of Pogorelov and Andreev, a polytope $P$ admits a realisation in Lobachevsky space $\mathbb{L}^3$ with right dihedral angles if and only if $P \in \mathcal{P}$. We consider two families of smooth manifolds defined by regular 4-colourings of Pogorelov polytopes P: six-dimensional quasitoric manifolds over $P$ and three-dimensional small covers of $P$; the latter are also known as three-dimensional hyperbolic manifolds of Loebell type. We prove that two manifolds from either of the families are diffeomorphic if and only if the corresponding 4-colourings are equivalent.

math.AT↗
arXiv2015

Embedding theorems for quasitoric manifolds

The study of embeddings of smooth manifolds into Euclidean and projective spaces has been for a long time an important area in topology. In this paper we obtain improvements of classical results on embeddings of smooth manifolds, focusing on the case of quasitoric manifolds. We give explicit constructions of equivariant embeddings of a quasitoric manifold described by combinatorial data $(P,Λ)$ into Euclidean and complex projective space. This construction provides effective bounds on the dimension of the equivariant embedding.

math.AT↗
arXiv2014

Toric Topology

Toric topology emerged in the end of the 1990s on the borders of equivariant topology, algebraic and symplectic geometry, combinatorics and commutative algebra. It has quickly grown up into a very active area with many interdisciplinary links and applications, and continues to attract experts from different fields. The key players in toric topology are moment-angle manifolds, a family of manifolds with torus actions defined in combinatorial terms. Their construction links to combinatorial geometry and algebraic geometry of toric varieties via the related notion of a quasitoric manifold. Discovery of remarkable geometric structures on moment-angle manifolds led to seminal connections with the classical and modern areas of symplectic, Lagrangian and non-Kaehler complex geometry. A related categorical construction of moment-angle complexes and their generalisations, polyhedral products, provides a universal framework for many fundamental constructions of homotopical topology. The study of polyhedral products is now evolving into a separate area of homotopy theory, with strong links to other areas of toric topology. A new perspective on torus action has also contributed to the development of classical areas of algebraic topology, such as complex cobordism. The book contains lots of open problems and is addressed to experts interested in new ideas linking all the subjects involved, as well as to graduate students and young researchers ready to enter into a beautiful new area.

math.AT↗
arXiv2012

Hopf algebras and homotopy invariants

In this paper we explore new relations between Algebraic Topology and the theory of Hopf Algebras. For an arbitrary topological space $X$, the loop space homology $H_*(ΩΣX; \coefZ)$ is a Hopf algebra. We introduce a new homotopy invariant of a topological space $X$ taking for its value the isomorphism class (over the integers) of the Hopf algebra $H_*(ΩΣX; \coefZ)$. This invariant is trivial if and only if the Hopf algebra $H_*(ΩΣX; \coefZ)$ is isomorphic to a Lie-Hopf algebra, that is, to a primitively generated Hopf algebra. We show that for a given $X$ these invariants are obstructions to the existence of a homotopy equivalence $ΣX\simeq Σ^2Y$ for some space $Y$. Further on, using the notion of Hopf algebras, we establish new structural properties of the cohomology ring, in particular, of the cup product. For example, using the fact that the suspension of a polyhedral product $X$ is a double suspension, we obtain a strong condition on the cohomology ring structure of $X$. This gives an important application in toric topology. For an algebra to be realised as the cohomology ring of a moment-angle manifold $\Z_P$ associated to a simple polytope $P$, we found an obstruction in the Hopf algebra $H_*(ΩΣ\Z_P)$. In addition, we use homotopy decompositions to study particular Hopf algebras.

math.AT↗
arXiv2006

Dieudonné modules and $p$-divisible groups associated with Morava $K$-theory of Eilenberg-Mac Lane spaces

We study the structure of the formal groups associated to the Morava $K$-theories of integral Eilenberg-Mac Lane spaces. The main result is that every formal group in the collection $\{K(n)^*K({\mathbb Z}, q), q=2,3,...\}$ for a fixed $n$ enters in it together with its Serre dual, an analogue of a principal polarization on an abelian variety. We also identify the isogeny class of each of these formal groups over an algebraically closed field. These results are obtained with the help of the Dieudonné correspondence between bicommutative Hopf algebras and Dieudonné modules. We extend P. Goerss's results on the bilinear products of such Hopf algebras and corresponding Dieudonné modules.

math.AT↗
arXiv2004

Hyperelliptic addition law

We construct an explicit form of the addition law for hyperelliptic Abelian vector functions $\wp$ and $\wp'$. The functions $\wp$ and $\wp'$ form a basis in the field of hyperelliptic Abelian functions, i.e., any function from the field can be expressed as a rational function of $\wp$ and $\wp'$.

math-ph↗
arXiv1996

Hyperelliptic Kleinian functions and applications

We develop the theory of hyperelliptic Kleinian functions. As applications we consider construction of the explicit matrix realization of the hyperelliptic Kummer varieties, differential operators to have the hyperelliptic curve as spectral variety, solution of the KdV equations by Kleinian functions.

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