1,605 research outputs found
Tame combing and almost convexity conditions
We give the first examples of groups which admit a tame combing with linear
radial tameness function with respect to any choice of finite presentation, but
which are not minimally almost convex on a standard generating set. Namely, we
explicitly construct such combings for Thompson's group F and the
Baumslag-Solitar groups BS(1, p) with p \ge 3. In order to make this
construction for Thompson's group F, we significantly expand the understanding
of the Cayley complex of this group with respect to the standard finite
presentation. In particular we describe a quasigeodesic set of normal forms and
combinatorially classify the arrangements of 2-cells adjacent to edges that do
not lie on normal form paths.Comment: 36 pages, 9 figure
Genetic Influences on Brain Gene Expression in Rats Selected for Tameness and Aggression
Inter-individual differences in many behaviors are partly due to genetic
differences, but the identification of the genes and variants that influence
behavior remains challenging. Here, we studied an F2 intercross of two outbred
lines of rats selected for tame and aggressive behavior towards humans for more
than 64 generations. By using a mapping approach that is able to identify
genetic loci segregating within the lines, we identified four times more loci
influencing tameness and aggression than by an approach that assumes fixation
of causative alleles, suggesting that many causative loci were not driven to
fixation by the selection. We used RNA sequencing in 150 F2 animals to identify
hundreds of loci that influence brain gene expression. Several of these loci
colocalize with tameness loci and may reflect the same genetic variants.
Through analyses of correlations between allele effects on behavior and gene
expression, differential expression between the tame and aggressive rat
selection lines, and correlations between gene expression and tameness in F2
animals, we identify the genes Gltscr2, Lgi4, Zfp40 and Slc17a7 as candidate
contributors to the strikingly different behavior of the tame and aggressive
animals
Marden's Tameness Conjecture: history and applications
Marden's Tameness Conjecture predicts that every hyperbolic 3-manifold with
finitely generated fundamental group is homeomorphic to the interior of a
compact 3-manifold. It was recently established by Agol and Calegari-Gabai. We
will survey the history of work on this conjecture and discuss its many
applications.Comment: 30 pages, expository article based on a lecture given at the
conference on "Geometry, Topology and Analysis of Locally Symmetric Spaces
and Discrete Groups'' held in Beijing in July 2007. Article was published in
the proceedings of that conferenc
State Tameness: A New Approach for Credit Constrains
We propose a new definition for tameness within the model of security prices as It\^o processes that is risk-aware. We give a new definition for arbitrage and characterize it. We then prove a theorem that can be seen as an extension of the second fundamental theorem of asset pricing, and a theorem for valuation of contingent claims of the American type. The valuation of European contingent claims and American contingent claims that we obtain does not require the full range of the volatility matrix. The technique used to prove the theorem on valuation of American contingent claims does not depend on the Doob-Meyer decomposition of super-martingales; its proof is constructive and suggest and alternative way to find approximations of stopping times that are close to optimal.arbitrage, pricing of contingent claims, continuous-time financial markets, tameness
The inhomogeneous Dirichlet Problem for natural operators on manifolds
We shall discuss the inhomogeneous Dirichlet problem for: where is a "natural" differential operator, with a restricted
domain , on a manifold . By "natural" we mean operators that arise
intrinsically from a given geometry on . An important point is that the
equation need not be convex and can be highly degenerate. Furthermore, the
inhomogeneous term can take values at the boundary of the restricted domain
of the operator . A simple example is the real Monge-Amp\`ere operator on a riemannian manifold , where
is the riemannian Hessian, the restricted domain is , and is continuous with .
A main new tool is the idea of local jet-equivalence, which gives rise to
local weak comparison, and then to comparison under a natural and necessary
global assumption.
The main theorem applies to pairs , which are locally jet-equivalent
to a given constant coefficient pair . This covers a large
family of geometric equations on manifolds: orthogonally invariant operators on
a riemannian manifold, G-invariant operators on manifolds with G-structure,
operators on almost complex manifolds, and operators, such as the Lagrangian
Monge-Amp\`ere operator, on symplectic manifolds. It also applies to all
branches of these operators.
Complete existence and uniqueness results are established with existence
requiring the same boundary assumptions as in the homogeneous case [10]. We
also have results where the inhomogeneous term is a delta function.Comment: Some minor addition
Tameness in least fixed-point logic and McColm's conjecture
We investigate four model-theoretic tameness properties in the context of
least fixed-point logic over a family of finite structures. We find that each
of these properties depends only on the elementary (i.e., first-order) limit
theory, and we completely determine the valid entailments among them. In
contrast to the context of first-order logic on arbitrary structures, the order
property and independence property are equivalent in this setting. McColm
conjectured that least fixed-point definability collapses to first-order
definability exactly when proficiency fails. McColm's conjecture is known to be
false in general. However, we show that McColm's conjecture is true for any
family of finite structures whose limit theory is model-theoretically tame
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