We prove that both the hyperelliptic mapping class group and the extended hyperelliptic mapping class group are generated by two torsion elements. We also compute the index of the subgroup of the hyperelliptic mapping class group which is generated by involutions and we prove that the extended hyperelliptic mapping cla…
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Study of hyperelliptic mapping class groups with applications and profinite completions.
Paper computes rational cohomology of spin hyperelliptic mapping class groups.
Study identifies roots of hyperelliptic involutions and braid groups in mapping class groups.
Nonorientable surfaces have a faithful linear representation of a specific dimension.
The paper studies power subgroups of Dehn twists in hyperelliptic mapping class groups.
Study on cohomology of spin hyperelliptic mapping class groups.
The hyperelliptic Torelli group is the subgroup of the mapping class group consisting of elements that act trivially on the homology of the surface and that also commute with some fixed hyperelliptic involution. The authors and Putman proved that this group is generated by Dehn twists about separating curves fixed by t…
We obtain a simple presentation of the hyperelliptic mapping class group of a nonorientable surface N. As an application we compute the first homology group of with coefficients in .
We consider the hyperelliptic handlebody group on a closed surface of genus . This is the subgroup of the mapping class group on a closed surface of genus consisting of isotopy classes of homeomorphisms on the surface that commute with some fixed hyperelliptic involution and that extend to homeomorphisms on the …
Study of liftable mapping class group for superelliptic covers.
We give a new upper bound on the stable commutator length of Dehn twists in hyperelliptic mapping class groups, and determine the stable commutator length of some elements. We also calculate values and the defects of homogeneous quasimorphisms derived from ω-signatures, and show that they are linearly independent in th…
Classifies periodic diffeomorphisms and hyperelliptic involutions on surfaces.
The hyperelliptic Torelli group is the subgroup of the mapping class group consisting of elements that act trivially on the homology of the surface and that also commute with some fixed hyperelliptic involution. We prove a Birman exact sequence for hyperelliptic Torelli groups, and we show that this sequence splits. As…
A hyperelliptic broken Lefschetz fibration is a generalization of a hyperelliptic Lefschetz fibration. We construct and compute a local signature of hyperelliptic directed broken Lefschetz fibrations by generalizing Endo's local signature of hyperelliptic Lefschetz fibrations. It is described by his local signature and…
Constructs correspondences on hyperelliptic surfaces combining orbifold groups and Blaschke products.
New group-theoretic Johnson classes applied to curves with torsion Ceresa classes.
S. Bigelow proved that the braid groups are linear. That is, there is a faithful representation of the braid group into the general linear group of some field. Using this, we deduce from previously known results that the mapping class group of a sphere with punctures and hyperelliptic mapping class groups are linear. I…
Study Picard groups of curves with symmetry, focusing on abelian groups and hyperelliptic curves.
Study shows monodromy kernels are large, failing to prove commensurability in specific strata.
We give a complete description of conjugacy classes of finite subgroups of the mapping class group of the sphere with r marked points. As a corollary we obtain a description of conjugacy classes of maximal finite subgroups of the hyperelliptic mapping class group. In particular, we prove that for a fixed genus g there …
Study automorphisms and Torelli groups of right-angled Artin groups.
In this paper, we discuss relations among several invariants of 3-manifolds including Meyer's function, the eta-invariant, the von Neumann rho-invariant and the Casson invariant from the viewpoint of the mapping class group of a surface.
Study of lifting maps in branched covers of 3-manifolds, showing non-injectivity.
The paper studies maps on graphs and their fibers, focusing on hyperelliptic graphs.
We give new upper bounds on the stable commutator lengths of Dehn twists in mapping class groups and new lower bounds on the stable commutator lengths of Dehn twists in hyperelliptic mapping class groups. In particular, we show that the stable commutator lengths of Dehn twists about a nonseparating and a separating cur…
We construct a relation among right-handed Dehn twists in the mapping class group of a compact oriented surface of genus g with 4g+4 boundary components. This relation gives an explicit topological description of 4g+4 disjoint (-1)-sections of a hyperelliptic Lefschetz fibration of genus g on the manifold {CP}^2#(4g+5)…
In this paper we prove that finite index subgroups of genus 3 mapping class and Torelli groups that contain the group generated by Dehn twists on bounding simple closed curves are not Kahler. These results are deduced from explicit presentations of the unipotent (aka, Malcev) completion of genus 3 Torelli groups and of…
Finite subgroups of good groups correspond to their profinite completions.
The study examines pseudo-Anosov maps on curve complexes and their asymptotic translation lengths.
We present a formula expressing Earle's twisted 1-cocycle on the mapping class group of a closed oriented surface of genus >=2 relative to a fixed base point, with coefficients in the first homology group of the surface. For this purpose we compare it with Morita's twisted 1-cocycle which is combinatorial. The key is t…
Study on second homology group of genus 3 hyperelliptic Torelli group.
Proves a minimal generating set for a specific group of mapping classes.
We prove that the hyperelliptic Torelli group is generated by Dehn twists about separating curves that are preserved by the hyperelliptic involution. This verifies a conjecture of Hain. The hyperelliptic Torelli group can be identified with the kernel of the Burau representation evaluated at t=-1 and also the fundament…
The paper classifies homomorphisms between braid groups and mapping class groups.
New findings on generating mapping class groups using pseudo-Anosov elements.
Formula for signature of handlebody bundles, interpreting cohomology.
Let SI(S_g) denote the hyperelliptic Torelli group of a closed surface S_g of genus g. This is the subgroup of the mapping class group of S_g consisting of elements that act trivially on H_1(S_g;Z) and that commute with some fixed hyperelliptic involution of S_g. We prove that the cohomological dimension of SI(S_g) is …
The study finds that many mapping class groups have normal generators.
For each d>=2, the mapping class group for plane curves of degree d will be defined and it is proved that there exists uniquely the Meyer function on this group. In the case of d=4, using our Meyer function, we can define the local signature for 4-dimensional fiber spaces whose general fibers are non-hyperelliptic comp…
For any positive integer , we exhibit a cofinite subgroup of the mapping class group of a surface of genus at most two such that admits an epimorphism onto a free group of rank . We conclude that has rank at least and the dimension of the second bounded cohomology of each of these ma…
A palindrome in a free group F_n is a word on some fixed free basis of F_n that reads the same backwards as forwards. The palindromic automorphism group ΠA_n of the free group F_n consists of automorphisms that take each member of some fixed free basis of F_n to a palindrome; the group ΠA_n has close connections with h…
We investigate the rigidity and asymptotic properties of quantum SU(2) representations of mapping class groups. In the spherical braid group case the trivial representation is not isolated in the family of quantum SU(2) representations. In particular, they may be used to give an explicit check that spherical braid grou…
The paper studies liftable mapping class groups of cyclic covers of spheres.
Study vanishing cycles on curves in toric surfaces, identifying specific types of obstructions.
The purpose of this note is to explain a combinatorial description of closed smooth oriented 4-manifolds in terms of positive Dehn twist factorizations of surface mapping classes, and further explore these connections. This is obtained via monodromy representations of simplified broken Lefschetz fibrations on 4-manifol…
Researchers describe a Ceresa class for tropical and topological curves, linking algebraic and cohomological perspectives.
The paper studies mapping class groups of cyclic covers and their liftable counterparts.