Concept
Mapping class group
Related publications (20)
Bounded and unbounded cohomology of homeomorphism and diffeomorphism groups
We determine the bounded cohomology of the group of homeomorphisms of certain low-dimensional manifolds. In particular, for the group of orientation-preserving homeomorphisms of the circle and of the closed 2-disc, it is isomorphic to the polynomial ring g ...
SPRINGER HEIDELBERG2023Non-Hermitian time evolution: From static to parametric instability
Romain Christophe Rémy Fleury, Aleksi Antoine Bossart
Eigenmode coalescence imparts remarkable properties to non-Hermitian time evolution, culminating in a purely non-Hermitian spectral degeneracy known as an exceptional point (EP). Here, we revisit time evolution around EPs, looking at both static and period ...
2021Coherent actions by homeomorphisms on the real line or an interval
We study actions of groups by orientation preserving homeomorphisms on R (or an interval) that are minimal, have solvable germs at +/-infinity and contain a pair of elements of a certain dynamical type. We call such actions coherent. We establish that such ...
HEBREW UNIV MAGNES PRESS2020Approximating nonabelian free groups by groups of homeomorphisms of the real line
We show that for a large class C of finitely generated groups of orientation preserving homeomorphisms of the real line, the following holds: Given a group G of rank k in C, there is a sequence of k-markings (G,S-n), n is an element of N whose limit in the ...
2020Structural Properties Of Dendrite Groups
Let G be the homeomorphism group of a dendrite. We study the normal subgroups of G. For instance, there are uncountably many nonisomorphic such groups G that are simple groups. Moreover, these groups can be chosen so that any isometric G-action on any metr ...
AMER MATHEMATICAL SOC2019Kaleidoscopic groups: permutation groups constructed from dendrite homeomorphisms
Given a transitive permutation group, a fundamental object for studying its higher transitivity properties is the permutation action of its isotropy subgroup. We reverse this relationship and introduce a universal construction of infinite permutation group ...
POLISH ACAD SCIENCES INST MATHEMATICS-IMPAN2019Twisting structures and morphisms up to strong homotopy
We define twisted composition products of symmetric sequences via classifying morphisms rather than twisting cochains. Our approach allows us to establish an adjunction that simultaneously generalizes a classic one for algebras and coalgebras, and the bar- ...
2019The cup product of Brooks quasimorphisms
We prove the vanishing of the cup product of the bounded cohomology classes associated to any two Brooks quasimorphisms on the free group. This is a consequence of the vanishing of the square of a universal class for tree automorphism groups. ...
WALTER DE GRUYTER GMBH2018Modular functors, cohomological field theories, and topological recursion
Given a topological modular functor V in the sense of Walker, we construct vector bundles Z (lambda) over bar, over (M) over bar (g,n) whose Chern characters define semi-simple cohomological field theories. This construction depends on a determinati ...
AMER MATHEMATICAL SOC2018Nielsen Equivalence In Gupta-Sidki Groups
For a group G generated by k elements, the Nielsen equivalence classes are defined as orbits of the action of AutF(k), the automorphism group of the free group of rank k, on the set of generating k-tuples of G. Let p >= 3 be prime and G(p) the Gupta-Sidki ...
Amer Mathematical Soc2017