The identification and exploitation of almost symmetry in planning problems

Previous work in symmetry detection for planning has identified symmetries between domain objects and shown how the exploitation of this information can help reduce search at plan time. However these methods are unable to detect symmetries between objects that are almost symmetrical: where the objects must start (or end) in slightly different configurations but for much of the plan their behaviour is equivalent. In the paper we outline a method for identifying such symmetries and discuss how this symmetry information can be positively exploited to help direct search during planning we have implemented this method and integrated it with the FF-v2.3 planner and in the paper we present results of experiments with this approach that demonstrate its potential

Point symmetries in the Hartree-Fock approach: Symmetry-breaking schemes

We analyze breaking of symmetries that belong to the double point group D2h(TD) (three mutually perpendicular symmetry axes of the second order, inversion, and time reversal). Subgroup structure of the D2h(TD) group indicates that there can be as much as 28 physically different, broken-symmetry mean-field schemes --- starting with solutions obeying all the symmetries of the D2h(TD) group, through 26 generic schemes in which only a non-trivial subgroup of D2h(TD) is conserved, down to solutions that break all of the D2h(TD) symmetries. Choices of single-particle bases and the corresponding structures of single-particle hermitian operators are discussed for several subgroups of D2h(TD).Comment: 10 RevTeX pages, companion paper in nucl-th/991207

Non-local meta-conformal invariance, diffusion-limited erosion and the XXZ chain

Diffusion-limited erosion is a distinct universality class of fluctuating interfaces. Although its dynamical exponent $z=1$, none of the known variants of conformal invariance can act as its dynamical symmetry. In $d=1$ spatial dimensions, its infinite-dimensional dynamic symmetry is constructed and shown to be isomorphic to the direct sum of three loop-Virasoro algebras, with the maximal finite-dimensional sub-algebra $\mathfrak{sl}(2,\mathbb{R})\oplus\mathfrak{sl}(2,\mathbb{R})\oplus\mathfrak{sl}(2,\mathbb{R})$. The infinitesimal generators are spatially non-local and use the Riesz-Feller fractional derivative. Co-variant two-time response functions are derived and reproduce the exact solution of diffusion-limited erosion. The relationship with the terrace-step-kind model of vicinal surfaces and the integrable XXZ chain are discussed.Comment: Latex 2e, 28 pp, 4 figures (revised, with 2 new figures

Audio Description Washes Brighter? A Study in Brand Names and Advertising

Dealing with objects in audio description, and particularly with those objects that have a clear designer imprint or branding, is a complex matter when a brand name is part of the scene in a film. Deciding whether to describe or not, and how, becomes more than a technical matter that depends on text–image synchronization: it is a complex decision-making process comparable to other forms of audiovisual translation that needs to be approached as a paradigmatic example of intersemiotic translation. Dávila-Montes and Orero address the audio description of branded objects in movies, and their intersemiotic translation from images to spoken words, a complex issue that may harbour additional insights into topics of a wider scope

Hierarchical models for service-oriented systems

We present our approach to the denotation and representation of hierarchical graphs: a suitable algebra of hierarchical graphs and two domains of interpretations. Each domain of interpretation focuses on a particular perspective of the graph hierarchy: the top view (nested boxes) is based on a notion of embedded graphs while the side view (tree hierarchy) is based on gs-graphs. Our algebra can be understood as a high-level language for describing such graphical models, which are well suited for defining graphical representations of service-oriented systems where nesting (e.g. sessions, transactions, locations) and linking (e.g. shared channels, resources, names) are key aspects