Carlos T. Simpson

  1. Fixed points and lines in 2-metric spaces.

    Authors: Carlos T. Simpson, Abdelkrim Aliouche
    Subjects: Metric Geometry
    Abstract

    We consider bounded 2-metric spaces satisfying an additional axiom, and show
    that a contractive mapping has either a fixed point or a fixed line.

  2. Homotopy theory of higher categories.

    Authors: Carlos T. Simpson
    Subjects: Category Theory
    Abstract

    This is the first draft of a book about higher categories approached by
    iterating Segal's method, as in Tamsamani's definition of $n$-nerve and
    Pelissier's thesis. If $M$ is a tractable left proper cartesian model category,
    we construct a tractable left proper cartesian model structure on the category
    of $M$-precategories. The procedure can then be iterated, leading to model
    categories of $(\infty, n)$-categories.

  3. Obstructed bundles of rank two on a quintic surface.

    Authors: Nicole Mestrano, Carlos T. Simpson
    Subjects: Algebraic Geometry
    Abstract

    In this note we consider the moduli space of stable bundles of rank two on a
    very general quintic surface. We study the obstructed points of the moduli
    space via the spectral covering of a twisted endomorphism. This analysis leads
    in some examples to a generically non-reduced component of the moduli space,
    and a component which is generically smooth of one bigger than the expected
    dimension. We obtain a sharp bound asked for by O'Grady saying when the moduli
    space is good.

  4. Obstructed bundles of rank two on a quintic surface.

    Authors: Nicole Mestrano, Carlos T. Simpson
    Subjects: Algebraic Geometry
    Abstract

    In this note we consider the moduli space of stable bundles of rank two on a
    very general quintic surface. We study the obstructed points of the moduli
    space via the spectral covering of a twisted endomorphism. This analysis leads
    in some examples to a generically non-reduced component of the moduli space,
    and a component which is generically smooth of one bigger than the expected
    dimension. We obtain a sharp bound asked for by O'Grady saying when the moduli
    space is good.

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