170 research outputs found
On the uniformization of L-valued frames
This note discusses the appropriate way of uniformizing the notion
of an L-valued frame introduced by A. Pultr and S. Rodabaugh in [Lattice-valued
frames, functor categories, and classes of sober spaces, Chapter 6 of Topological
and Algebraic Structures in Fuzzy Sets: A Handbook of Recent Developments in
the Mathematics of Fuzzy Sets, Kluwer, 2003]. It covers the case of a completely
distributive lattice L (which is, in a certain sense, the most general one) and studies
the corresponding category of uniform L-valued frames
The densest lattices in PGL3(Q2)
We find the smallest possible covolume for lattices in PGL3(Q2), show that
there are exactly two lattices with this covolume, and describe them
explicitly. They are commensurable, and one of them appeared in Mumford's
construction of his fake projective plane. We also discuss a new 2-adic
uniformization of another fake projective plane.Comment: Minor error correcte
Liouville and Toda field theories on Riemann surfaces
We study the Liouville theory on a Riemann surface of genus g by means of
their associated Drinfeld--Sokolov linear systems. We discuss the cohomological
properties of the monodromies of these systems. We identify the space of
solutions of the equations of motion which are single--valued and local and
explicitly represent them in terms of Krichever--Novikov oscillators. Then we
discuss the operator structure of the quantum theory, in particular we
determine the quantum exchange algebras and find the quantum conditions for
univalence and locality. We show that we can extend the above discussion to
Toda theories.Comment: 41 pages, LaTeX, SISSA-ISAS 27/93/E
On the p-adic uniformization of unitary Shimura curves
We prove -adic uniformization for Shimura curves attached to the group of
unitary similitudes of certain binary skew hermitian spaces with respect to
an arbitrary CM field with maximal totally real subfield . For a place
of that is not split in and for which is anisotropic, let
be an extension of to the reflex field . We define an integral
model of the corresponding Shimura curve over by
means of a moduli problem for abelian schemes with suitable polarization and
level structure prime to . The formulation of the moduli problem involves a
Kottwitz condition, an Eisenstein condition, and an adjusted invariant. The
first two conditions are conditions on the Lie algebra of the abelian
varieties; the last condition is a condition on the Riemann form of the
polarization. The uniformization of the formal completion of this model along
its special fiber is given in terms of the formal Drinfeld upper half plane for
. The proof relies on the construction of the contracting functor which
relates a relative Rapoport-Zink space for strict formal -modules with
a Rapoport-Zink space of -divisible groups which arise from the moduli
problem, where the -action is usually not strict when . Our main tool is the theory of displays, in particular the Ahsendorf
functor.Comment: 145 page
The basic locus of the unitary Shimura variety with parahoric level structure, and special cycles
In this paper, we study the basic locus in the fiber at of a certain
unitary Shimura variety with a certain parahoric level structure. The basic
locus is uniformized by a formal scheme
which is called Rapoport-Zink space. We show that the irreducible
components of the induced reduced subscheme of
are Deligne-Lusztig varieties and their intersection behavior is
controlled by a certain Bruhat-Tits building. Also, we define special cycles in
and study their intersection multiplicities.Comment: 54 page
From non-commutative diagrams to anti-elementary classes
Anti-elementarity is a strong way of ensuring that a class of structures , in
a given first-order language, is not closed under elementary equivalence with
respect to any infinitary language of the form L . We prove
that many naturally defined classes are anti-elementary, including the
following: the class of all lattices of finitely generated convex
{\ell}-subgroups of members of any class of {\ell}-groups containing all
Archimedean {\ell}-groups; the class of all semilattices of finitely
generated {\ell}-ideals of members of any nontrivial quasivariety of
{\ell}-groups; the class of all Stone duals of spectra of
MV-algebras-this yields a negative solution for the MV-spectrum Problem;
the class of all semilattices of finitely generated two-sided ideals
of rings; the class of all semilattices of finitely generated
submodules of modules; the class of all monoids encoding the
nonstable -theory of von Neumann regular rings, respectively C*-algebras
of real rank zero; (assuming arbitrarily large Erd"os cardinals) the
class of all coordinatizable sectionally complemented modular lattices with a
large 4-frame. The main underlying principle is that under quite general
conditions, for a functor : A B, if there exists a
non-commutative diagram D of A, indexed by a common sort of poset called an
almost join-semilattice, such that D^I is a commutative
diagram for every set I, D is not isomorphic to X for
any commutative diagram X in A, then the range of is anti-elementary.Comment: 49 pages. Journal of Mathematical Logic, World Scientific Publishing,
In pres
T-duality Twists and Asymmetric Orbifolds
We study some aspects of asymmetric orbifolds of tori, with the orbifold
group being some subgroup of the T-duality group and, in
particular, provide a concrete understanding of certain phase factors that may
accompany the T-duality operation on the stringy Hilbert space in toroidal
compactification. We discuss how these T-duality twist phase factors are
related to the symmetry and locality properties of the closed string vertex
operator algebra, and clarify the role that they enact in the modular
covariance of the orbifold theory, mainly using asymmetric orbifolds of tori
which are root lattices as working examples.Comment: 67 pages. v2: references added and typos correcte
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