598 research outputs found
On Higher Order Gravities, Their Analogy to GR, and Dimensional Dependent Version of Duff's Trace Anomaly Relation
An almost brief, though lengthy, review introduction about the long history
of higher order gravities and their applications, as employed in the
literature, is provided. We review the analogous procedure between higher order
gravities and GR, as described in our previous works, in order to highlight its
important achievements. Amongst which are presentation of an easy
classification of higher order Lagrangians and its employment as a
\emph{criteria} in order to distinguish correct metric theories of gravity. For
example, it does not permit the inclusion of only one of the second order
Lagrangians in \emph{isolation}. But, it does allow the inclusion of the
cosmological term. We also discuss on the compatibility of our procedure and
the Mach idea. We derive a dimensional dependent version of Duff's trace
anomaly relation, which in \emph{four}-dimension is the same as the usual Duff
relation. The Lanczos Lagrangian satisfies this new constraint in \emph{any}
dimension. The square of the Weyl tensor identically satisfies it independent
of dimension, however, this Lagrangian satisfies the previous relation only in
three and four dimensions.Comment: 30 pages, added reference
Classical Trace Anomaly
We seek an analogy of the mathematical form of the alternative form of
Einstein's field equations for Lovelock's field equations. We find that the
price for this analogy is to accept the existence of the trace anomaly of the
energy-momentum tensor even in classical treatments. As an example, we take
this analogy to any generic second order Lagrangian and exactly derive the
trace anomaly relation suggested by Duff. This indicates that an intrinsic
reason for the existence of such a relation should perhaps be, classically,
somehow related to the covariance of the form of Einstein's equations.Comment: Version 2: 21 pages, TeX file (using phyzzx.tex), added new section
and references. Version 3: Just replaced Abstrac
The Witten equation, mirror symmetry and quantum singularity theory
For any non-degenerate, quasi-homogeneous hypersurface singularity, we
describe a family of moduli spaces, a virtual cycle, and a corresponding
cohomological field theory associated to the singularity. This theory is
analogous to Gromov-Witten theory and generalizes the theory of r-spin curves,
which corresponds to the simple singularity A_{r-1}.
We also resolve two outstanding conjectures of Witten. The first conjecture
is that ADE-singularities are self-dual; and the second conjecture is that the
total potential functions of ADE-singularities satisfy corresponding
ADE-integrable hierarchies. Other cases of integrable hierarchies are also
discussed.Comment: To appear in Annals of Mathematics. Includes resolution of the Witten
ADE integrable hierarchies conjecture and Witten's ADE self-mirror
conjecture. Several corrections and clarification
The Hilbert Zonotope and a Polynomial Time Algorithm for Universal Grobner Bases
We provide a polynomial time algorithm for computing the universal Gr\"obner
basis of any polynomial ideal having a finite set of common zeros in fixed
number of variables. One ingredient of our algorithm is an effective
construction of the state polyhedron of any member of the Hilbert scheme
Hilb^d_n of n-long d-variate ideals, enabled by introducing the Hilbert
zonotope H^d_n and showing that it simultaneously refines all state polyhedra
of ideals on Hilb^d_n
Holographic Heat Current as Noether Current
We employ the Noether procedure to derive a general formula for the radially
conserved heat current in AdS planar black holes with certain transverse and
traceless perturbations, for a general class of gravity theories. For Einstein
gravity, the general higher-order Lovelock gravities and also a class of
Horndeski gravities, we derive the boundary stress tensor and show that the
resulting boundary heat current matches precisely the bulk Noether current.Comment: Latex, 27 pages, typos corrected, comments added, references adde
A Stein variational Newton method
Stein variational gradient descent (SVGD) was recently proposed as a general
purpose nonparametric variational inference algorithm [Liu & Wang, NIPS 2016]:
it minimizes the Kullback-Leibler divergence between the target distribution
and its approximation by implementing a form of functional gradient descent on
a reproducing kernel Hilbert space. In this paper, we accelerate and generalize
the SVGD algorithm by including second-order information, thereby approximating
a Newton-like iteration in function space. We also show how second-order
information can lead to more effective choices of kernel. We observe
significant computational gains over the original SVGD algorithm in multiple
test cases.Comment: 18 pages, 7 figure
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