238 research outputs found
Parsing of Spoken Language under Time Constraints
Spoken language applications in natural dialogue settings place serious
requirements on the choice of processing architecture. Especially under adverse
phonetic and acoustic conditions parsing procedures have to be developed which
do not only analyse the incoming speech in a time-synchroneous and incremental
manner, but which are able to schedule their resources according to the varying
conditions of the recognition process. Depending on the actual degree of local
ambiguity the parser has to select among the available constraints in order to
narrow down the search space with as little effort as possible.
A parsing approach based on constraint satisfaction techniques is discussed.
It provides important characteristics of the desired real-time behaviour and
attempts to mimic some of the attention focussing capabilities of the human
speech comprehension mechanism.Comment: 19 pages, LaTe
Algebraic geometry over algebraic structures II: Foundations
In this paper we introduce elements of algebraic geometry over an arbitrary
algebraic structure. We prove Unification Theorems which gather the description
of coordinate algebras by several ways.Comment: 55 page
Fermionic Matrix Models
We review a class of matrix models whose degrees of freedom are matrices with
anticommuting elements. We discuss the properties of the adjoint fermion one-,
two- and gauge invariant D-dimensional matrix models at large-N and compare
them with their bosonic counterparts which are the more familiar Hermitian
matrix models. We derive and solve the complete sets of loop equations for the
correlators of these models and use these equations to examine critical
behaviour. The topological large-N expansions are also constructed and their
relation to other aspects of modern string theory such as integrable
hierarchies is discussed. We use these connections to discuss the applications
of these matrix models to string theory and induced gauge theories. We argue
that as such the fermionic matrix models may provide a novel generalization of
the discretized random surface representation of quantum gravity in which the
genus sum alternates and the sums over genera for correlators have better
convergence properties than their Hermitian counterparts. We discuss the use of
adjoint fermions instead of adjoint scalars to study induced gauge theories. We
also discuss two classes of dimensionally reduced models, a fermionic vector
model and a supersymmetric matrix model, and discuss their applications to the
branched polymer phase of string theories in target space dimensions D>1 and
also to the meander problem.Comment: 139 pages Latex (99 pages in landscape, two-column option); Section
on Supersymmetric Matrix Models expanded, additional references include
Complete hierarchies of efficient approximations to problems in entanglement theory
We investigate several problems in entanglement theory from the perspective
of convex optimization. This list of problems comprises (A) the decision
whether a state is multi-party entangled, (B) the minimization of expectation
values of entanglement witnesses with respect to pure product states, (C) the
closely related evaluation of the geometric measure of entanglement to quantify
pure multi-party entanglement, (D) the test whether states are multi-party
entangled on the basis of witnesses based on second moments and on the basis of
linear entropic criteria, and (E) the evaluation of instances of maximal output
purities of quantum channels. We show that these problems can be formulated as
certain optimization problems: as polynomially constrained problems employing
polynomials of degree three or less. We then apply very recently established
known methods from the theory of semi-definite relaxations to the formulated
optimization problems. By this construction we arrive at a hierarchy of
efficiently solvable approximations to the solution, approximating the exact
solution as closely as desired, in a way that is asymptotically complete. For
example, this results in a hierarchy of novel, efficiently decidable sufficient
criteria for multi-particle entanglement, such that every entangled state will
necessarily be detected in some step of the hierarchy. Finally, we present
numerical examples to demonstrate the practical accessibility of this approach.Comment: 14 pages, 3 figures, tiny modifications, version to be published in
Physical Review
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