A classification of $S^3$-bundles over $S^4$

Classification of equivariant vector bundles over real projective plane

We classify equivariant topological complex vector bundles over real projective plane under a compact Lie group (not necessarily effective) action. It is shown that nonequivariant Chern classes and isotropy representations at (at most) three points are sufficient to classify equivariant vector bundles over real projective plane except one case. To do it, we relate the problem to classification on two-sphere through the covering map because equivariant vector bundles over two-sphere have been already classified.

Classification of equivariant vector bundles over two-torus

We exhaustively classify topological equivariant complex vector bundles over two-torus under a compact Lie group (not necessarily effective) action. It is shown that inequivariant Chern classes and isotropy representations at (at most) six points are sufficient to classify equivariant vector bundles except a few cases. To do it, we calculate homotopy of the set of equivariant clutching maps. And, classification on real projective plane, Klein bottle will appear soon

圆上等变复向量丛的分类

Classification of Equivariant Complex Vector Bundles over a Circle

本文通过刻画纤维表示并研究表示扩张，分类了圆上等变复向量丛，并由此计算了任意紧李群作用下圆的约化等变K群。

Homotopy Classification of Line Bundles Over Rigid Analytic Varieties

We construct a motivic homotopy theory for rigid analytic varieties with the rigid analytic affine line $\mathbb{A} ^1_\mathrm{rig}$ as an interval object. This motivic homotopy theory is inspired from, but not equal to, Ayoub's motivic homotopy theory for rigid analytic varieties. Working in the so constructed homotopy theory, we prove that a homotopy classification of vector bundles of rank $n$ over rigid analytic quasi-Stein spaces follows from $\mathbb{A}^1_\mathrm{rig}$-homotopy invariance of vector bundles. This $\mathbb{A}^1_\mathrm{rig}$-homotopy invariance is equivalent to a rigid ana…

圆上等变实向量丛的分类

Classification of equivariant real vector bundles over a circle

本文延续作者先前对圆上等变复向量丛的分类研究，通过刻画纤维表示并利用复情形结果，分类了具有紧李群作用的圆上等变实向量丛，并讨论其平凡性。

A cohomological classification of vector bundles on smooth affine threefolds

We give a cohomological classification of vector bundles of rank $2$ on a smooth affine threefold over an algebraically closed field having characteristic unequal to $2$. As a consequence we deduce that cancellation holds for rank $2$ vector bundles on such varieties. The proofs of these results involve three main ingredients. First, we give a description of the first non-stable ${\mathbb A}^1$-homotopy sheaf of the symplectic group. Second, these computations can be used in concert with F. Morel's ${\mathbb A}^1$-homotopy classification of vector bundles on smooth affine schemes and obstructi…

$S^{2k-1}$纤维 over $S^{2k}$的同调分类

Homotopy classification of $S^{2k-1}$-bundles over $S^{2k}$

本文研究了$S^{2k-1}$纤维 over $S^{2k}$的总空间同调类型，提出新的条件判断CW复形是否同调等价于球面纤维总空间，并在k=2,4时给出 attaching map 与 characteristic map 的关系公式，k=4时推翻了[6]中的猜想。

Locally homogeneous connections on principal bundles over hyperbolic Riemann surfaces

Let $g$ be locally homogeneous (LH) Riemannian metric on a differentiable compact manifold $M$, and $K$ be a compact Lie group endowed with an $\mathrm {ad}$-invariant inner product on its Lie algebra $\mathfrak{k}$. A connection $A$ on a principal $K$-bundle $p:P\to M$ on $M$ is locally homogeneous if for any two points $x_1$, $x_2\in M$ there exists an isometry $φ:U_1\to U_2$ between open neighborhoods $U_i\ni x_i$ which sends $x_1$ to $x_2$ and admits a $φ$-covering bundle isomorphism preserving the connection $A$. This condition is invariant under the action of the automorphism group (gaug…

Principal bundles on 2-dimensional CW-complexes with disconnected structure group

Given any topological group $G$, the topological classification of principal $G$-bundles over a finite CW-complex $X$ is long-known to be given by the set of free homotopy classes of maps from $X$ to the corresponding classifying space $BG$. This classical result has been long-used to provide such classification in terms of explicit characteristic classes. However, even when $X$ has dimension $2$, it seems there is a case in which such explicit classification has not been explicitly considered. This is the case where $G$ is a Lie group, whose group of components acts non-trivially on its funda…

On the Topology of Real Bundle Pairs over Nodal Symmetric Surfaces

We give an alternative argument for the classification of real bundle pairs over smooth symmetric surfaces and extend this classification to nodal symmetric surfaces. We also classify the homotopy classes of automorphisms of real bundle pairs over symmetric surfaces. The two statements together describe the isomorphisms between real bundle pairs over symmetric surfaces up to deformation.

闭合定向曲面上的可定向环面束的分类

Classification of orientable torus bundles over closed orientable surfaces

本文研究了闭合定向曲面上的可定向环面束的分类问题，通过分析映射类群作用下的同态分类，给出了束同构下的完整分类结果，并探讨了其在拓扑扩展问题中的应用。

关于光滑实仿射曲面和三次曲面向量包的上同调分类

On the cohomological classification of vector bundles on smooth real affine surfaces and threefolds

本文研究光滑实仿射曲面和三次曲面上的向量包的上同调分类，证明在适当的上同调条件下，这种分类与在代数闭基域上由Mohan Kumar和Murthy以及Asok和Fasel得到的分类相吻合，并给出了Kucharz关于三次曲面上秩3向量包的Chern类的代数循环三元组的定理的高效证明，同时回答了Kucharz留下的问题，给出了首个实仿射三次曲面上具有平凡Chern类但非稳定自由的射影模。

复射影5维空间上的复秩3向量丛分类

A classification of complex rank 3 vector bundles on complex projective 5-space

该研究明确了复射影5维空间上秩3拓扑丛的同构类数与陈类的关系，构造$\boldsymbol{\textit{Z}}/3$值不变量区分同陈类的不同丛，完善了陈类不完备性的相关结论。

Classification of Q-trivial Bott manifolds

A Bott manifold is a closed smooth manifold obtained as the total space of an iterated $\C P^1$-bundle starting with a point, where each $\C P^1$-bundle is the projectivization of a Whitney sum of two complex line bundles. A \emph{$\Q$-trivial Bott manifold} of dimension $2n$ is a Bott manifold whose cohomology ring is isomorphic to that of $(\CP^1)^n$ with $\Q$-coefficients. We find all diffeomorphism types of $\Q$-trivial Bott manifolds and show that they are distinguished by their cohomology rings with $\Z$-coefficients. As a consequence, we see that the number of diffeomorphism classes in …

On the cohomology equivalences between bundle-type quasitoric manifolds over a cube

The aim of this article is to establish the notion of bundle-type quasitoric manifolds and provide two classification results on them: (1) ($\mathbb{C}P^2\sharp\mathbb{C}P^2$)-bundle type quasitoric manifolds are weakly equivariantly homeomorphic if their cohomology rings are isomorphic, and (2) quasitoric manifolds over $I^3$ are homeomorphic if their cohomology rings are isomorphic. In the latter case, there are only four quasitoric manifolds up to weakly equivariant homeomorphism which are not bundle-type.

Bundles of spectra and algebraic K-theory

A parametrized spectrum E is a family of spectra E_x continuously parametrized by the points x of a topological space X. We take the point of view that a parametrized spectrum is a bundle-theoretic geometric object. When R is a ring spectrum, we consider parametrized R-module spectra and show that they give cocycles for the cohomology theory determined by the algebraic K-theory K(R) of R in a manner analogous to the description of topological K-theory K^0(X) as the Grothendieck group of vector bundles over X. We prove a classification theorem for parametrized spectra, showing that parametrized…

Fiber bundles over Alexandroff spaces

We introduce a topological variant of the Grothendieck construction which serves to represent every fiber bundle over an Alexandroff space. Using this result we give a classification theorem for fiber bundles over Alexandroff spaces with T$_0$ fiber and we construct a universal bundle for bundles with T$_0$ fiber over posets which are cofibrant objects of the category of small categories. Moreover, we prove that our construction induces an equivalence of categories between a suitable category of functors and the category of fiber bundles over a fixed Alexandroff space. In addition, we prove th…

Projective bundles over toric surfaces

Let $E$ be the Whitney sum of complex line bundles over a topological space $X$. Then, the projectivization $P(E)$ of $E$ is called a \emph{projective bundle} over $X$. If $X$ is a non-singular complete toric variety, so is $P(E)$. In this paper, we show that the cohomology ring of a non-singular projective toric variety $M$ determines whether it admits a projective bundle structure over a non-singular complete toric surface. In addition, we show that two 6-dimensional projective bundles over 4-dimensional quasitoric manifolds are diffeomorphic if their cohomology rings are isomorphic as grade…

Classification of real Bott manifolds

A real Bott manifold is the total space of a sequence of $\R P^1$ bundles starting with a point, where each $\R P^1$ bundle is projectivization of a Whitney sum of two real line bundles. A real Bott manifold is a real toric manifold which admits a flat riemannian metric. An upper triangular $(0,1)$ matrix with zero diagonal entries uniquely determines such a sequence of $\R P^1$ bundles but different matrices may produce diffeomorphic real Bott manifolds. In this paper we determine when two such matrices produce diffeomorphic real Bott manifolds. The argument also proves that any graded ring i…

Comparing A^1-h-cobordism and A^1-weak equivalence

We study the problem of classifying projectivizations of rank-two vector bundles over ${\mathbb P}^2$ up to various notions of equivalence that arise naturally in ${\mathbb A}^1$-homotopy theory, namely ${\mathbb A}^1$-weak equivalence and ${\mathbb A}^1$-$h$-cobordism. First, we classify such varieties up to ${\mathbb A}^1$-weak equivalence: over algebraically closed fields having characteristic unequal to two the classification can be given in terms of characteristic classes of the underlying vector bundle. When the base field is ${\mathbb C}$, this classification result can be compared to a…