1,532 research outputs found
Systematic Derivation of Bounds and Glue Constraints for Time-Series Constraints
slides corresponding to this paperInteger time series are often subject to constraints on the aggregation of the integer features of all occurrences of some pattern within the series. For example, the number of inflexions may be constrained, or the sum of the peak maxima, or the minimum of the peak widths. It is currently unknown how to maintain domain consistency efficiently on such constraints. We propose parametric ways of systematically deriving glue constraints, which are a particular kind of implied constraints, as well as aggregation bounds that can be added to the decomposition of time-series constraints [5]. We evaluate the beneficial propagation impact of the derived implied constraints and bounds, both alone and together
On the T-dual renormalisation of entanglement entropy
Imposing T-duality in the renormalisation process of entanglement entropy
leads to new relations between entanglement entropy counter-terms. T-duality is
made explicit by means of the generalised metric of double field theory in the
context of bulk-boundary duality. Double field theory in the bulk naturally
provides the new relations between higher order quantum corrections to
entanglement entropy as well as a systematic approach to understanding
entanglement entropy renormalisation counter-terms. An analogue for
Slavnov-Taylor identities for T-dual counter-terms of entanglement entropy is
envisaged
A Survey of Word Reordering in Statistical Machine Translation: Computational Models and Language Phenomena
Word reordering is one of the most difficult aspects of statistical machine
translation (SMT), and an important factor of its quality and efficiency.
Despite the vast amount of research published to date, the interest of the
community in this problem has not decreased, and no single method appears to be
strongly dominant across language pairs. Instead, the choice of the optimal
approach for a new translation task still seems to be mostly driven by
empirical trials. To orientate the reader in this vast and complex research
area, we present a comprehensive survey of word reordering viewed as a
statistical modeling challenge and as a natural language phenomenon. The survey
describes in detail how word reordering is modeled within different
string-based and tree-based SMT frameworks and as a stand-alone task, including
systematic overviews of the literature in advanced reordering modeling. We then
question why some approaches are more successful than others in different
language pairs. We argue that, besides measuring the amount of reordering, it
is important to understand which kinds of reordering occur in a given language
pair. To this end, we conduct a qualitative analysis of word reordering
phenomena in a diverse sample of language pairs, based on a large collection of
linguistic knowledge. Empirical results in the SMT literature are shown to
support the hypothesis that a few linguistic facts can be very useful to
anticipate the reordering characteristics of a language pair and to select the
SMT framework that best suits them.Comment: 44 pages, to appear in Computational Linguistic
Brane inflation and the WMAP data: a Bayesian analysis
The Wilkinson Microwave Anisotropy Probe (WMAP) constraints on string
inspired ''brane inflation'' are investigated. Here, the inflaton field is
interpreted as the distance between two branes placed in a flux-enriched
background geometry and has a Dirac-Born-Infeld (DBI) kinetic term. Our method
relies on an exact numerical integration of the inflationary power spectra
coupled to a Markov-Chain Monte-Carlo exploration of the parameter space. This
analysis is valid for any perturbative value of the string coupling constant
and of the string length, and includes a phenomenological modelling of the
reheating era to describe the post-inflationary evolution. It is found that the
data favour a scenario where inflation stops by violation of the slow-roll
conditions well before brane annihilation, rather than by tachyonic
instability. Concerning the background geometry, it is established that log(v)
> -10 at 95% confidence level (CL), where "v" is the dimensionless ratio of the
five-dimensional sub-manifold at the base of the six-dimensional warped
conifold geometry to the volume of the unit five-sphere. The reheating energy
scale remains poorly constrained, Treh > 20 GeV at 95% CL, for an extreme
equation of state (wreh ~ -1/3) only. Assuming the string length is known, the
favoured values of the string coupling and of the Ramond-Ramond total
background charge appear to be correlated. Finally, the stochastic regime
(without and with volume effects) is studied using a perturbative treatment of
the Langevin equation. The validity of such an approximate scheme is discussed
and shown to be too limited for a full characterisation of the quantum effects.Comment: 65 pages, 15 figures, uses iopart. Shortened version, updated
references. Matches publication up to appendix B kept on the arXi
JIMWLK evolution of the odderon
We study the effects of a parity-odd "odderon" correlation in Jalilian-Marian-Iancu-McLerran-Weigert-Leonidov-Kovner renormalization group evolution at high energy. Firstly we show that in the eikonal picture where the scattering is described by Wilson lines, one obtains a strict mathematical upper limit for the magnitude of the odderon amplitude compared to the parity-even Pomeron one. This limit increases with N-c, approaching infinity in the infinite N-c limit. We use a systematic extension of the Gaussian approximation including both two-and three-point correlations which enables us to close the system of equations even at finite N-c. In the large-N-c limit we recover an evolution equation derived earlier. By solving this equation numerically we confirm that the odderon amplitude decreases faster in the nonlinear case than in the linear Balitsky-Fadin-Kuraev-Lipatov limit. We also point out that, in the three-point truncation at finite N-c, the presence of an odderon component introduces azimuthal angular correlations similar to cos(n phi) at all n in the target color field. These correlations could potentially have an effect on future studies of multiparticle angular correlations.Peer reviewe
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