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Naive boundary strata and nilpotent orbits

Matt Kerr, Gregory Pearlstein (2014)

Annales de l’institut Fourier

We give a Hodge-theoretic parametrization of certain real Lie group orbits in the compact dual of a Mumford-Tate domain, and characterize the orbits which contain a naive limit Hodge filtration. A series of examples are worked out for the groups S U ( 2 , 1 ) , S p 4 , and G 2 .

Nesting maps of Grassmannians

Corrado De Concini, Zinovy Reichstein (2004)

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

Let F be a field and G r i , F n be the Grassmannian of i -dimensional linear subspaces of F n . A map f : G r i , F n G r j , F n is called nesting if l f l for every l G r i , F n . Glover, Homer and Stong showed that there are no continuous nesting maps G r i , C n G r j , C n except for a few obvious ones. We prove a similar result for algebraic nesting maps G r i , F n G r j , F n , where F is an algebraically closed field of arbitrary characteristic. For i = 1 this yields a description of the algebraic sub-bundles of the tangent bundle to the projective space P F n .

Non-Archimedean integrals and stringy Euler numbers of log-terminal pairs

Victor V. Batyrev (1999)

Journal of the European Mathematical Society

Using non-Archimedian integration over spaces of arcs of algebraic varieties, we define stringy Euler numbers associated with arbitrary Kawamata log-terminal pairs. There is a natural Kawamata log-terminal pair corresponding to an algebraic variety V having a regular action of a finite group G . In this situation we show that the stringy Euler number of this pair coincides with the physicists’ orbifold Euler number defined by the Dixon-Harvey-Vafa-Witten formula. As an application, we prove a conjecture...

Non-obstructed subcanonical space curves.

Rosa M. Miró-Roig (1992)

Publicacions Matemàtiques

Recall that a closed subscheme X ⊂ P is non-obstructed if the corresponding point x of the Hilbert scheme Hilbp(t)n is non-singular. A geometric characterization of non-obstructedness is not known even for smooth space curves. The goal of this work is to prove that subcanonical k-Buchsbaum, k ≤ 2, space curves are non-obstructed. As a main tool we use Serre's correspondence between subcanonical curves and vector bundles.

Non-uniruledness and the cancellation problem

Robert Dryło (2005)

Annales Polonici Mathematici

Using the notion of uniruledness we indicate a class of algebraic varieties which have a stronger version of the cancellation property. Moreover, we give an affirmative solution to the stable equivalence problem for non-uniruled hypersurfaces.

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