17:00 -- 18:30 数理科学研究科棟(東京大学駒場キャンパス)
Tea: 16:30 -- 17:00 コモンルーム
Last updated March 29, 2017
4月11日 -- 056号室, 17:00 -- 18:30
Alexander Voronov (University of Minnesota)
Homotopy Lie algebroids
Abstract: A well-known result of A. Vaintrob [Vai97]
characterizes Lie algebroids and their morphisms in terms of homological vector fields on supermanifolds.
We give an interpretation of Lie bialgebroids and their morphisms in terms of odd symplectic dg-manifolds,
building on the approach of D. Roytenberg[Roy99].
This extends naturally to the homotopy Lie case and leads to the notion of
L∞-bialgebroids and L∞-morphisms between them.
4月25日 -- 056号室, 17:00 -- 18:30
久野 雄介 (津田塾大学)
Formality of the Goldman-Turaev Lie bialgebra and the Kashiwara-Vergne problem in positive genus
Abstract: This talk is based on a joint work with A. Alekseev, N. Kawazumi and F. Naef.
Given a compact oriented surface with non-empty boundary and a framing of the surface,
one can define the Lie bracket (Goldman bracket) and the Lie cobracket (Turaev bracket)
on the vector space spanned by free homotopy classes of loops on the surface.
These maps are of degree minus two with respect to a certain filtration.
Then one can ask the formality of this Lie bialgebra:
is the Goldman-Turaev Lie bialgebra isomorphic to its associated graded?
For surfaces of genus zero, we showed that this question is closely related to the Kashiwara-Vergne (KV) problem in Lie theory (arXiv:1703.05813).
A similar result was obtained by G. Massuyeau by using the Kontsevich integral.
Our new topological interpretation of the classical KV problem leads us
to introduce a generalization of the KV problem in connection with the formality of the Goldman-Turaev Lie bialgebra for surfaces of positive genus.
We will discuss the existence and uniqueness of solutions to the generalized KV problem.
5月9日 -- 056号室, 17:00 -- 18:30
諏訪 立雄 (北海道大学)
Local and global coincidence homology classes
Abstract: We consider two differentiable maps between two oriented manifolds.
In the case the manifolds are compact with the same dimension and the coincidence points are isolated,
there is the Lefschetz coincidence point formula, which generalizes his fixed point formula.
In this talk we discuss the case where the dimensions of the manifolds may possible be different so that the coincidence points are not isolated in general.
In fact it seems that Lefschetz himself already considered this case (cf. ).
We introduce the local and global coincidence homology classes and state a general coincidence point theorem.
We then give some explicit expressions for the local class.
We also take up the case of several maps as considered in  and perform similar tasks.
These all together lead to a generalization of the aforementioned Lefschetz formula.
The key ingredients are the Alexander duality in combinatorial topology,
intersection theory with maps and the Thom class in Čech-de Rham cohomology.
The contents of the talk are in  and .
 C. Biasi, A.K.M. Libardi and T.F.M. Monis, The Lefschetz coincidence class of p maps, Forum Math. 27 (2015), 1717-1728.
 C. Bisi, F. Bracci, T. Izawa and T. Suwa,
Localized intersection of currents and the Lefschetz coincidence point theorem, Annali di Mat. Pura ed Applicata 195 (2016), 601-621.
 J.-P. Brasselet and T. Suwa, Local and global coincidence homology classes, arXiv:1612.02105.
 N.E. Steenrod, The work and influence of Professor Lefschetz in algebraic topology,
Algebraic Geometry and Topology: A Symposium in Honor of Solomon Lefschetz, Princeton Univ. Press 1957, 24-43.