The Torsion of Homology Groups of M(E,I)-sets

A functorial control of integral torsion in homology

We study the integral torsion of the values of strict polynomial functors defined over the integers. We interpret some classical homological invariants as values of strict polynomial functors and therefore obtain estimates of the integral torsion of these invariants, including cancellation results.

On torsion in homology of singular toric varieties

Let $X$ be a toric variety. Rationally Borel-Moore homology of $X$ is isomorphic to the homology of the Koszul complex $A^T_*(X)\otimes Λ^\x M$, where $A^T_*(X)$ is the equivariant Chow group and $M$ is the character group of $T$. Moreover, the same holds for coefficients which are the integers with certain primes inverted.

Torsion in Khovanov homology of homologically thin knots

We prove that every $\mathbb{Z}_2$H-thin link has no $2^k$-torsion for $k>1$ in its Khovanov homology. Together with previous results by Eun Soo Lee and the author, this implies that integer Khovanov homology of non-split alternating links is completely determined by the Jones polynomial and signature. Our proof is based on establishing an algebraic relation between Bockstein and Turner differentials on Khovanov homology over $\mathbb{Z}_2$. We conjecture that a similar relation exists between the corresponding spectral sequences.

Khovanov homology: torsion and thickness

We partially solve the conjecture by A.Shumakovitch about torsion in the Khovanov homology of prime, non-split links in S^3. We give a size restriction on the Khovanov homology of almost alternating links. We relate the Khovanov homology of the connected sum of a link diagram and the Hopf link with the Khovanov homology of the diagram via a short exact sequence of homology which splits. Finally we show that our results can be adapted to reduced Khovanov homology and we show that there is a long exact sequence connecting reduced Khovanov homology with unreduced homology.

挠敏感相交同调的拓扑不变性

Topological invariance of torsion sensitive intersection homology

本文研究挠敏感相交同调的拓扑不变性，证明其定义层复形在拟同构意义下对分层选择的独立性，并推广经典不变性定理且获得经典情形下的新结果。

The stable homotopy classification of $(n-1)$-connected $(n+4)$-dimensional polyhedra with 2 torsion free homology

In this paper, we study the stable homotopy types of $\mathbf{F}^4_{n(2)}$-polyhedra, i.e., $(n-1)$-connected, at most $(n+4)$-dimensional polyhedra with 2-torsion free homologies. We are able to classify the indecomposable $\mathbf{F}^4_{n(2)}$-polyhedra. The proof relies on the matrix problem technique which was developed in the classification of representaions of algebras and applied to homotopy theory by Baues and Drozd.

Finsler空间中的几何障碍与无 torsion 持续同调

Geometric Obstructions in Finsler Spaces and Torsion-Free Persistent Homology

本文研究Finsler空间中拓扑数据分析与持续同调的关联，通过整数矩阵分解寻找素数p以提取自由部分的孔结构。

关于Erdős–Rényi随机图的欧拉数量同调中的挠元

On torsion in eulerian magnitude homology of Erdos-Renyi random graphs

本文通过引入欧拉Asao–Izumihara复形并建立其剥脱消失阈值，确定了Erdős–Rényi随机图欧拉数量同调群无挠的参数区间。

三维复空间中超平面排列的Milnor纤维边界同调群中的偶 torsion

Even torsions in the homology group of the Milnor fiber boundary of hyperplane arrangements in $\mathbb{C}^3$

本文研究三维复空间中超平面排列的Milnor纤维边界同调群，证明在某些条件下，第一同调群的偶阶torsion分解数大于等于项目化补集的欧拉示性。

On growth of homology torsion in amenable groups

Suppose an amenable group $G$ is acting freely on a simply connected simplicial complex $\tilde X$ with compact quotient $X$. Fix $n \geq 1$, assume $H_n(\tilde X, \mathbb{Z})=0$ and let $(H_i)$ be a Farber chain in $G$. We prove that the torsion of the integral homology in dimension $n$ of $\tilde{X}/H_i$ grows subexponentially in $[G:H_i]$. By way of contrast, if $X$ is not compact, there are solvable groups of derived length 3 for which torsion in homology can grow faster than any given function.

Stable comparison of multidimensional persistent homology groups with torsion

The present lack of a stable method to compare persistent homology groups with torsion is a relevant problem in current research about Persistent Homology and its applications in Pattern Recognition. In this paper we introduce a pseudo-distance d_T that represents a possible solution to this problem. Indeed, d_T is a pseudo-distance between multidimensional persistent homology groups with coefficients in an Abelian group, hence possibly having torsion. Our main theorem proves the stability of the new pseudo-distance with respect to the change of the filtering function, expressed both with resp…

Torsion homology and regulators of isospectral manifolds

Given a finite group G, a G-covering of closed Riemannian manifolds, and a so-called G-relation, a construction of Sunada produces a pair of manifolds M_1 and M_2 that are strongly isospectral. Such manifolds have the same dimension and the same volume, and their rational homology groups are isomorphic. We investigate the relationship between their integral homology. The Cheeger-Mueller Theorem implies that a certain product of orders of torsion homology and of regulators for M_1 agrees with that for M_2. We exhibit a connection between the torsion in the integral homology of M_1 and M_2 on th…

持续同调中的挠率与神经网络

Torsion in Persistent Homology and Neural Networks

本文研究挠率在融合拓扑数据分析的自编码器中的作用，发现标准域系数方法会丢失或改变挠率信息，并强调需设计保留挠率特征的架构或损失项以提升数据表示稳健性。

自由环路空间有理同调与挠同伦群中的指数增长

Exponential growth in the rational homology of free loop spaces and in torsion homotopy groups

本文利用积分方法推广了自由环路空间有理同调群增长的结果，构造出同伦群$p$-挠指数增长的新空间族，并提出有理同伦群与$p$-挠同伦群指数增长间存在紧密联系的猜想。

Rational torus-equivariant stable homotopy V: the torsion Adams spectral sequence

We provide a calculational method for rational stable equivariant homotopy theory for a torus G based on the homology of the Borel construction on fixed points. More precisely we define an abelian torsion model, A_t(G) of finite injective dimension, a homology theory \piAt_* taking values in A_t(G) based on the homology of the Borel construction, and a finite Adams spectral sequence Ext_{A_t(G)}^{*,*}(\piAt_*(X), \piAt_*(Y)) ==> [X,Y]^G_* for rational G-spectra X and Y.

Cohen--Lenstra heuristics for torsion in homology of random complexes

We study torsion in homology of the random $d$-complex $Y \sim Y_d(n,p)$ experimentally. Our experiments suggest that there is almost always a moment in the process where there is an enormous burst of torsion in homology $H_{d-1}(Y)$. This moment seems to coincide with the phase transition studied in \cite{AL,LP,LP3} , where cycles in $H_d(Y)$ first appear with high probability. Our main study is the limiting distribution on the $q$-part of the torsion subgroup of $H_{d-1}(Y)$ for small primes $q$. We find strong evidence for a limiting Cohen--Lenstra distribution, where the probability that t…

Detecting torsion in skein modules using Hochschild homology

Given a Heegaard splitting of a closed 3-manifold, the skein modules of the two handlebodies are modules over the skein algebra of their common boundary surface. The zeroth Hochschild homology of the skein algebra of a surface with coefficients in the tensor product of the skein modules of two handlebodies is interpreted as the skein module of the 3-manifold obtained by gluing the two handlebodies together along this surface. A spectral sequence associated to the Hochschild complex is constructed and conditions are given for the existence of algebraic torsion in the skein module of this 3-mani…

Torsion homology and cellular approximation

In this note we describe the role of the Schur multiplier in the structure of the $p$-torsion of discrete groups. More concretely, we show how the knowledge of $H_2G$ allows to approximate many groups by colimits of copies of finite $p$-groups. Our examples include interesting families of non-commutative infinite groups, including Burnside groups, certain solvable examples and the first Grigorchuk group. We also provide a counterexample for a conjecture of E. Farjoun.

Double coverings of arrangement complements and $2$-torsion in Milnor fiber homology

We prove that the mod $2$ Betti numbers of double coverings of a complex hyperplane arrangement complement are combinatorially determined. The proof is based on a relation between the mod $2$ Aomoto complex and the transfer long exact sequence. Applying the above result to the icosidodecahedral arrangement ($16$ planes in the three dimensional space related to the icosidodecahedron), we conclude that the first homology of the Milnor fiber has non-trivial $2$-torsion.

具有无挠同调的$(n-2)$-连通$2n$维Poincaré复形研究

On $(n-2)$-connected $2n$-dimensional Poincaré complexes with torsion-free homology

该文研究具有无挠同调的$(n-2)$-连通$2n$维Poincaré复形，证明其可分解为两类Poincaré复形的连通和，在附加条件下可进一步分解，还应用结果分类了2-连通8维此类复形的同伦型。

The Homology groups of right pointed sets over a partially commutative monoid

We study the homology of pointed sets over a partially commutative monoid.

Small flag complexes with torsion

We classify flag complexes on at most 12 vertices with torsion in the first homology group. The result is moderately computer-aided. As a consequence we confirm a folklore conjecture that the smallest poset whose order complex is homotopy equivalent to the real projective plane (and also the smallest poset with torsion in the first homology group) has exactly 13 elements.

关于 magnitude（上）同调及其挠的有限生成性

On finite generation in magnitude (co)homology, and its torsion

本文应用 Sam-Snowden 框架证明有界亏格图的 magnitude 上同调秩多项式增长且挠有界，并推广至路径同调，同时证明相关平面图范畴拟 Gröbner。

Torsion in the space of commuting elements in a Lie group

Let $G$ be a compact connected Lie group, and let $\mathrm{Hom}(\mathbb{Z}^m,G)$ be the space of pairwise commuting $m$-tuples in $G$. We study the problem of which primes $p$ $\mathrm{Hom}(\mathbb{Z}^m,G)_1$, the connected component of $\mathrm{Hom}(\mathbb{Z}^m,G)$ containing the element $(1,\ldots,1)$, has $p$-torsion in homology. We will prove that $\mathrm{Hom}(\mathbb{Z}^m,G)_1$ for $m\ge 2$ has $p$-torsion in homology if and only if $p$ divides the order of the Weyl group of $G$ for $G=SU(n)$ and some exceptional groups. We will also compute the top homology of $\mathrm{Hom}(\mathbb{Z}^…

Small simplicial complexes with prescribed torsion in homology

For $d \geq 2$ and $G$ a finite abelian group, define $T_d(G)$ to be the minimum number of vertices $n$ so that there exists a simplicial complex $X$ on $n$ vertices which has the torsion part of $H_{d - 1}(X)$ isomorphic to $G$. Here we establish an upper bound on $T_d(G)$ which matches the known lower bound up to a constant factor. That is, we prove that for every $d \geq 2$ there exist constants $c_d$ and $C_d$ so that for any finite abelian group $c_d(\log |G|)^{1/d} \leq T_d(G) \leq C_d(\log |G|)^{1/d}.$

Edge Contractions and Simplicial Homology

We study the effect of edge contractions on simplicial homology because these contractions have turned to be useful in various applications involving topology. It was observed previously that contracting edges that satisfy the so called link condition preserves homeomorphism in low dimensional complexes, and homotopy in general. But, checking the link condition involves computation in all dimensions, and hence can be costly, especially in high dimensional complexes. We define a weaker and more local condition called the p-link condition for each dimension p, and study its effect on edge contra…

确定性超树的同调扭转增长

The homology torsion growth of determinantal hypertrees

研究确定性超树的同调群增长特性，证明其扭转增长常数范围。

Approximating L^2-invariants and homology growth

In this paper we consider the asymptotic behavior of invariants such as Betti numbers, minimal numbers of generators of singular homology, the order of the torsion subgroup of singular homology, and torsion invariants. We will show that all these vanish in the limit if the CW-complex under consideration fibers in a specific way. In particular we will show that all these vanish in the limit if one considers an aspherical closed manifold which admits a non-trivial S^1-action or whose fundamental group contains an infinite normal elementary amenable subgroup. By considering classifying spaces we …

内顺从群的挠同调增长与廉价重建

Torsion homology growth and cheap rebuilding of inner-amenable groups

本研究利用Tucker-Drob的内顺从群结构定理，证明了实质上无挠、剩余有限的非顺从内顺从群具有廉价1-重建性质，推导其第一ℓ²-Betti数与1次对数挠为零，将相关结果从顺从群推广到内顺从群。

Homology and homotopy complexity in negative curvature

Linear upper bounds are provided for the size of the torsion homology of negatively curved manifolds of finite volume in all dimensions $d\ne 3$. This extends a classical theorem by Gromov. In dimension $3$, as opposed to the Betti numbers, the size of torsion homology is unbounded in terms of the volume. Moreover, there is a sequence of $3$-dimensional hyperbolic manifolds that converges to $\mathbb{H}^3$ in the Benjamini--Schramm topology while its normalized torsion in the first homology is dense in $[0,\infty]$. In dimension $d\geq 4$ a somewhat precise estimate is given for the number of …

陈 - 西蒙斯型3 - 上循环与离散微分同胚群第三同调中的\(\mathbb{Q}/\mathbb{Z}\) - 挠率

Chern--Simons-type $3$-cocycles and $\mathbb{Q}/\mathbb{Z}$-torsion in the third homology of discrete diffeomorphism groups

研究标准3 - 球面相关群的第三整群同调，通过构造陈 - 西蒙斯型3 - 类、采用挠率控制局部积分方法等，证明其包含\((\mathbb{Q}/\mathbb{Z})^2\)，还在多种流形中检测到\(\mathbb{Q}/\mathbb{Z}\)。

Homology bounds for hyperbolic orbifolds

We will provide bounds on both the Betti numbers and the torsion part of the homology of hyperbolic orbifolds. These bounds are linear in the volume and are a direct consequence of an efficient simplicial model of the thick part, which we will construct as well. The homology statements complement previous work of Bader, Gelander and Sauer (torsion homology of manifolds), Samet (Betti numbers of orbifolds) and a classical theorem of Gromov (Betti numbers of manifolds). For arithmetic, non-compact hyperbolic orbifolds -- i.e. in the case of arithmetic, non-uniform lattices in $\operatorname{Isom…

A volume form on the Khovanov invariant

The Reidemeister torsion construction can be applied to the chain complex used to compute the Khovanov homology of a knot or a link. This defines a volume form on Khovanov homology. The volume form transforms correctly under Reidemeister moves to give an invariant volume on the Khovanov homology. In this paper, its construction and invariance under these moves is demonstrated. Also, some examples of the invariant are presented for particular choices for the bases of homology groups to obtain a numerical invariant of knots and links. In these examples, the algebraic torsion seen in the Khovanov…

On homology torsion growth

We prove new vanishing results on the growth of higher torsion homologies for suitable arithmetic lattices, Artin groups and mapping class groups. The growth is understood along Farber sequences, in particular, along residual chains. For principal congruence subgroups, we also obtain strong asymptotic bounds for the torsion growth. As a central tool, we introduce a quantitative homotopical method called effective rebuilding. This constructs small classifying spaces of finite index subgroups, at the same time controlling the complexity of the homotopy. The method easily applies to free abelian …

环面上无序点配置同调中的奇素数挠率

Odd-primary torsion in the homology of unordered configurations on the torus

研究环面\(\Sigma_1\)上无序点配置空间\(B_k(\Sigma_1)\)同调中的奇素数挠率。通过证明不同\(k\)值和奇素数\(p\)下\(H_*(B_k(\Sigma_1);\mathbb{Z})\)的\(p\) - 挠率情况，得出特定条件下的相关结论。

Homology and derived series of groups

In 1964, John Stallings established an important relationship between the low-dimensional homology of a group and its lower central series. We establish a similar relationship between the low-dimensional homology of a group and its derived series. We also define a torsion-free-solvable completion of a group that is analogous to the Malcev completion, with the role of the lower central series replaced by the derived series. We prove that the torsion-free-solvable completion is invariant under rational homology equivalence.

A computational framework for weighted simplicial homology

We provide a bottom up construction of torsion generators for weighted homology of a weighted complex over a discrete valuation ring $R=\mathbb{F}[[π]]$. This is achieved by starting from a basis for classical homology of the $n$-th skeleton for the underlying complex with coefficients in the residue field $\mathbb{F}$ and then lifting it to a basis for the weighted homology with coefficients in the ring $R$. Using the latter, a bijection is established between $n+1$ and $n$ dimensional simplices whose weight ratios provide the exponents of the $π$-monomials that generate each torsion summand …

Comodules and Landweber exact homology theories

We show that, if E is a Landweber exact ring spectrum, then the category of E_*E-comodules is equivalent to the localization of the category of BP_*BP-comodules with respect to the hereditary torsion theory of v_n-torsion comodules, where n is the height of E. In particular, the category of E(n)_*E(n)-comodules is equivalent to the category of (v_n^{-1}BP)_*(v_n^{-1}BP)-comodules. We also prove structure theorems for E_*E-comodules; we show every E_*E-comodule has a primitive, we classify the invariant radical ideals, and we prove a version of the Landweber filtration theorem.

(Co)Homology of Poset Lie Algebras

We investigate the (co)homological properties of two classes of Lie algebras that are constructed from any finite poset: the solvable class $\frak{gl}^\preceq$ and the nilpotent class $\frak{gl}^\prec$. We confirm the conjecture of Jollenbeck that says: every prime power $p^r\!\leq\!n\!-\!2$ appears as torsion in $H_\ast(\frak{nil}_n;\mathbb{Z})$, and every prime power $p^r\!\leq\!n\!-\!1$ appears as torsion in $H_\ast(\frak{sol}_n;\mathbb{Z})$. If $\preceq$ is a bounded poset, then the (co)homology of $\frak{gl}^\preceq$ is \emph{torsion-convex}, i.e. if it contains $p$-torsion, then it also …

Twisted second homology groups of the automorphism group of a free group

In this paper, we compute the second homology groups of the automorphism group of a free group with coefficients in the abelianization of the free group and its dual group except for 2-torsion part, using combinatorial group theory.

Khovanov Homology: categorification of the Kauffman bracket relation

Khovanov homology offers a nontrivial generalization of Jones polynomial of links in R^3 (and of Kauffman bracket skein module of some 3-manifolds). In this chapter (Chapter X) we define Khovanov homology of links in R^3 and generalize the construction into links in an I-bundle over a surface. We use Viro's approach to construction of Khovanov homology and utilize the fact that one works with unoriented diagrams (unoriented framed links) in which case there is a simple description of Khovanov long exact sequence of homology. Khovanov homology, over the field Q, is a categorification of the Jon…

循环双结的集合论Yang-Baxter上同调

Set-theoretic Yang-Baxter cohomology of cyclic biquandles

本文完全确定了有限循环双结的集合论Yang-Baxter（上）同调群的自由部分，计算了低维同调群的挠子群，给出了高维挠阶的上界，部分解决了规范化同调猜想，并引入了非平凡的挠同调类。

廉价嵌入原理：同调增长的动力学上界

The cheap embedding principle: Dynamical upper bounds for homology growth

本文在度量群论框架下，为群的对数挠同调增长和贝蒂数增长建立了动力学上界。

对于无 torsion ample 群oids 的 Chern 符号

Chern character for torsion-free ample groupoids

本文构建了从 Baum-Connes 组合映射域到 Crainic-Moerdijk 群oids 带有有理系数的同调群的 Chern 符号映射，验证了 Matui 的 HK 猜想变体，并应用于超几何动力系统、拓扑满群同调等。

Equivariant $K$-homology for hyperbolic reflection groups

We compute the equivariant $K$-homology of the classifying space for proper actions, for compact 3-dimensional hyperbolic reflection groups. This coincides with the topological $K$-theory of the reduced $C^\ast$-algebra associated to the group, via the Baum-Connes conjecture. We show that, for any such reflection group, the associated $K$-theory groups are torsion-free. As a result we can promote previous rational computations to integral compu- tations. Our proof relies on a new efficient algebraic criterion for checking torsion-freeness of K-theory groups, which could be applied to many othe…

图辫群同调中所有有限阶挠元

Torsion of every finite order in the homology of graph braid groups

本文确定了图辫群同调中所有有限阶挠元的结构，给出了显式代表元、最小图条件及无挠性判定，并证明了奇挠元首次出现的具体位置。

Topological Hochschild homology of maximal orders in simple Q-algebras

We calculate the topological Hochschild homology groups of a maximal order in a central algebra over the rationals. Since the positive-dimensional THH groups consist only of torsion, we do this one prime ideal at a time for all the nonzero prime ideals in the center of the maximal order. This allows us to reduce the problem to studying the THH groups of maximal orders A in simple algebras over Q_p. We show that the topological Hochschild homology of A/(p) splits as the tensor product of its Hochschild homology and the topological Hochschild homology of F_p. We use this result in Brun's spectra…

The Rohlin invariant and Z/2-valued invariants of homology spheres

In this paper we prove that the Rohlin invariant is the unique invariant inducing a homomorphism on the Torelli group. Using this result we generalize the construction of invariants of homology $3$-spheres from families of trivial 2-cocycles on the Torelli group given by Pitsch to include invariants with values on an abelian group with $2$-torsion.

Fundamental groups, homology equivalences and one-sided h-cobordisms

We give a sufficient and necessary condition of the fundamental group homomorphism of a map between manifolds to induce homology equivalences. Moreover, a classification of one-sided h-cobordism of manifolds up to diffeomorphisms is obtained, based on Quillen's plus construction with Whitehead torsions.

The 2-torsion in the second homology of the genus $3$ mapping class group

This work is NOT to be used as reference. First, because as C.F.~Bödigheimer and M.~Korkmaz pointed to us the computation of the $\mathbf{Z}_2$ factor that remained undecided in M.~Korkmaz and A. Stipsicz, {\em The second homology groups of mapping class groups of orientable surfaces.} Math. Proc. Camb. Phil. Soc., was shown to exist by Skasai, see hi Theorem 4.9 and Corollary 4.10 in {\em Lagrangian mapping class groups from a group homological point of view.} Algebr. Geom. Topol. 12 (2012), no. 1, 267--291. Second, because one could obtain this result by gathering old results in the literatu…

Hochschild homology of mod-$p$ motivic cohomology over algebraically closed fields

We perform Hochschild homology calculations in the algebro-geometric setting of motives. The motivic Hochschild homology coefficient ring contains torsion classes which arise from the mod-$p$ motivic Steenrod algebra and from generating functions on the natural numbers with finite non-empty support. Under the Betti realization, we recover Bökstedt's calculation of the topological Hochschild homology of finite prime fields.