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A remark on the homotopical dimension of some moduli spaces of stable Riemann surfaces

Gabriele Mondello (2008)

Journal of the European Mathematical Society

Using a result of Harer, we prove certain upper bounds for the homotopical/cohomological dimension of the moduli spaces of Riemann surfaces of compact type, of Riemann surfaces with rational tails and of Riemann surfaces with at most k rational components. These bounds would follow from conjectures of Looijenga and Roth–Vakil.

A remark on the Picard group of spin moduli space

Maurizio Cornalba (1991)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

We describe a number of classes in the Picard group of spin moduli space and determine the relations they satisfy; as an application we show that the Picard group in question contains 4-torsion elements.

A remarkable contraction of semisimple Lie algebras

Dmitri I. Panyushev, Oksana S. Yakimova (2012)

Annales de l’institut Fourier

Recently, E.Feigin introduced a very interesting contraction 𝔮 of a semisimple Lie algebra 𝔤 (see arXiv:1007.0646 and arXiv:1101.1898). We prove that these non-reductive Lie algebras retain good invariant-theoretic properties of 𝔤 . For instance, the algebras of invariants of both adjoint and coadjoint representations of 𝔮 are free, and also the enveloping algebra of 𝔮 is a free module over its centre.

A representation theorem for a class of rigid analytic functions

Victor Alexandru, Nicolae Popescu, Alexandru Zaharescu (2003)

Journal de théorie des nombres de Bordeaux

Let p be a prime number, p the field of p -adic numbers and p the completion of the algebraic closure of p . In this paper we obtain a representation theorem for rigid analytic functions on 𝐏 1 ( p ) C ( t , ϵ ) which are equivariant with respect to the Galois group G = G a l c o n t ( p / p ) , where t is a lipschitzian element of p and C ( t , ϵ ) denotes the ϵ -neighborhood of the G -orbit of t .

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