Gregor Masbaum’s research while affiliated with Paris Diderot University and other places

What is this page?


This page lists works of an author who doesn't have a ResearchGate profile or hasn't added the works to their profile yet. It is automatically generated from public (personal) data to further our legitimate goal of comprehensive and accurate scientific recordkeeping. If you are this author and want this page removed, please let us know.

Publications (47)


On the skein module of the product of a surface and a circle
  • Preprint

April 2018

·

1 Read

·

Gregor Masbaum

Let Sigma be a closed oriented surface of genus g. We show that the Kauffman bracket skein module of Sigma x S^1 over the field of rational functions in A has dimension at least 2^{2g+1}+2g-1.



Lollipop tree Gg\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$G_g$$\end{document}
The colorings associated to the highest weights in Case II\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathrm {II}$$\end{document}, Case III\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathrm {III}$$\end{document}, and Case IV\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathrm {IV}$$\end{document}. The leftmost part of Gg\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$G_g$$\end{document} is not drawn as it is colored zero. For the same reason the rightmost edge is not drawn in Case IV\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathrm {IV}$$\end{document} as c is zero. These graphs could be guessed by taking the smallest coloring which is rightmost on the graph and has the given type
An application of TQFT to modular representation theory
  • Article
  • Publisher preview available

November 2017

·

26 Reads

·

7 Citations

Inventiones mathematicae

For p≥5p5p\ge 5 a prime, and g≥3g3g\ge 3 an integer, we use Topological Quantum Field Theory (TQFT) to study a family of p-1p1p-1 highest weight modules Lp(λ)Lp(λ)L_p(\lambda ) for the symplectic group Sp(2g,K)Sp(2g,K){{\mathrm{Sp}}}(2g,K) where K is an algebraically closed field of characteristic p. This permits explicit formulae for the dimension and the formal character of Lp(λ)Lp(λ)L_p(\lambda ) for these highest weights.

View access options

On powers of half-twists in M(0,2n)

August 2016

·

8 Reads

·

2 Citations

Glasgow Mathematical Journal

We use elementary skein theory to prove a version of a result of Stylianakis who showed that under mild restrictions on m and n, the normal closure of the m-th power of a half-twist has infinite index in the mapping class group of a sphere with 2n punctures.


On powers of half-twists in M(0,2n)

August 2016

We use elementary skein theory to prove a version of a result of Stylianakis who showed that under mild restrictions on m and n, the normal closure of the m-th power of a half-twist has infinite index in the mapping class group of a sphere with 2n punctures.



Frattini and related subgroups of mapping class groups

May 2016

·

12 Reads

Proceedings of the Steklov Institute of Mathematics

Let I" (g,b) denote the orientation-preserving mapping class group of a closed orientable surface of genus g with b punctures. For a group G let I broken vertical bar (f) (G) denote the intersection of all maximal subgroups of finite index in G. Motivated by a question of Ivanov as to whether I broken vertical bar (f) (G) is nilpotent when G is a finitely generated subgroup of I" (g,b) , in this paper we compute I broken vertical bar (f) (G) for certain subgroups of I" (g,b) . In particular, we answer Ivanov's question in the affirmative for these subgroups of I"g,b.


New Perspectives on the Interplay between Discrete Groups in Low-Dimensional Topology and Arithmetic Lattices

January 2015

·

8 Reads

Oberwolfach Reports

This workshop brought together specialists in areas ranging from arithmetic groups to topological quantum field theory, with common interest in arithmetic aspects of discrete groups arising from topology. The meeting showed significant progress in the field and enhanced the many connections between its subbranches.


Frattini and Related Subgroups of Mapping Class Groups

December 2014

·

28 Reads

·

1 Citation

Труды Математического института им Стеклова

Let Gamma_{g,b} denote the orientation-preserving Mapping Class Group of a closed orientable surface of genus g with b punctures. For a group G let Phi_f(G) denote the intersection of all maximal subgroups of finite index in G. In this paper we prove several results about Phi_f(G) for certain subgroups of Gamma_{g,b}. In particular, this answers a question of Ivanov for these subgroups of Gamma_{g,b}.


Dimension formulas for some modular representations of the symplectic group in the natural characteristic

November 2011

·

42 Reads

·

5 Citations

Journal of Pure and Applied Algebra

We compare the dimensions of the irreducible Sp(2g,K)-modules over a field K of characteristic p constructed by Gow with the dimensions of the irreducible Sp(2g,F_p)-modules that appear in the first approximation to representations of mapping class groups of surfaces in Integral Topological Quantum Field Theory. For this purpose, we derive a trigonometric formula for the dimensions of Gow's representations. This formula is equivalent to a special case of a formula contained in unpublished work of Foulle. Our direct proof is simpler than the proof of Foulle's more general result, and is modeled on the proof of the Verlinde formula in TQFT.


Citations (36)


... More deep studies in this vein were carried out in [8,9]. Computational results were seen in [1,4,[10][11][12][15][16][17] and the references therein. However, skein modules still appear rather mysterious; there remain many open problems about structures, properties of skein modules, as well as connections to classical invariants. ...

Reference:

Kauffman bracket skein module of the $(3,3,3,3)$-pretzel link exterior
On the skein module of the product of a surface and a circle
  • Citing Article
  • April 2018

Proceedings of the American Mathematical Society

... More precisely, those invariants are elements of the ring of integers of Q(ζ), namely, Z[ζ]. The result was reproved in [MR97], generalized to all classical Lie types in [MW98,TY99], then to all Lie types by Le [Le03]. These results helped us relate the quantum invariants to other invariants such as the Casson invariant [Mur94,Mur95] and the Ohtsuki series [Oht95,Oht96,Le03]. ...

Integral modular categories and integrality of quantum invariants at roots of unity of prime order
  • Citing Article
  • December 1998

... where P m (µ i jk (L)) means the result of evaluating the polynomial P m at y i jk = µ i jk (L). For m = 3, we find the Cochran's formula (31), and for m ≥ 5 the formula is from [56], which obtains that the first non-vanishing coefficient of ∇ L (z) for algebraically split links with 5 components is equal to: where P 5 (µ i jk (L)) consists of 15 terms corresponding to the spanning trees of Γ 5 . ...

Matrix-tree theorems and the Alexander–Conway polynomial
  • Citing Conference Paper
  • September 2002

Geometry and Topology Monographs

... The trivalent graph notation derives many useful formulae of the Kauffman bracket and makes it easy for us to calculate the quantum representations. Masbaum [Mas17] proved that the normal closure of powers of half-twists has infinite index in mapping class groups of punctured spheres by the quantum representation of braid groups. He used elementary skein theory whereas Stylianakis [Sty15] used the Jones representation [Jon87]. ...

On powers of half-twists in M(0,2n)
  • Citing Article
  • August 2016

Glasgow Mathematical Journal

... For example, certain families of quantum representations are known to be asymptotically linear, i.e., the intersection of the kernel of all representations in a family is trivial ( [And06], [FWW02]). Many quantum representations are also known to be integral ( [Gil04]), and they can be used to study the modular representation theory of mapping class groups and symplectic groups ( [GM17]). ...

An application of TQFT to modular representation theory

Inventiones mathematicae

... After that, Korinman [12] studied non-prime case: He showed that the representations are irreducible when p is the product of two distinct odd primes and when p is square of an odd prime, and for some other p, decomposable examples have been given. In [7], they first studied the cases that are with boundary. They proved when p is an odd prime, the representations of any surfaces with one boundary component is irreducible. ...

Integral topological quantum field theory for a one-holed torus

Pacific Journal of Mathematics

... The natural inclusion i: S 1 × D 2 → S 1 × S 2 induces an epimorphism i * : K(S 1 × D 2 ) → K(S 1 × S 2 ). Following Masbaum's work in the case of the Kauffman bracket skein module [5], we will use the following method to parametrize the relations arising from sliding over the 2-handle. Pick two points A, B on γ, which decompose γ into two intervals γ ′ and γ ′′ . ...

The spin refined Kauffman bracket skein module ofS 1×S 2 and lens spaces
  • Citing Article
  • December 1996

manuscripta mathematica

... Remark that the TQFT described in Theorem 6.5 is different from those studied, for instance, in [34,5] in that the target category is not that of vector spaces. Rather, when working over a field, it seems to fit very well in the general framework of [4] where in particular a cp-rigid and cocomplete braided monoidal category is shown to be a 3dualisable object in the 4-category BrTens so that, as a consequence, there is an extended TQFT associated to it. ...

Three-manifold invariants derived from the Kauffman bracket
  • Citing Article
  • October 1992

Topology

... He defined this invariant in terms of the Feynman path integral. Rigorous definitions of the invariant for SU(2) have been given by[19,10,3,8]. Specially, in[10], Lickorish redefined the invariant introducing the linear skein theory and the Temperley–Lieb algebra. ...

Topological quantum ˉeld theories derived from the Kaufiman bracket
  • Citing Article