pinecone/core-2020-05-10-deduplication huggingface dataset:
Regularization and Quantization of Higher Dimensional Current Algebras

We present some recently discovered infinite dimensional Lie algebras that
can be understood as extensions of the algebra Map(M,g) of maps from a compact
p-dimensional manifold to some finite dimensional Lie algebra g. In the first
part of the paper, we describe the physical motivations for the study of these
algebras. In the second part, we discuss their realization in terms of
pseudo-differential operators and comment on their possible representation
theory.Comment: (Talk given at the G\"ursey Memorial Conference I on Strings and
  Symmetries, Istanbul, Turkey, June 6-10 1994.) 11 pages, plain TEX. ITP 94-1
Fermion masses and mixing from an extra gauge symmetry

Assuming that a horizontal abelian (gauge) symmetry is at the origin of texture zeros in the fermion mass matrices we show how realistic mass patterns can be generated in the presence of scalar fields whose vacuum expectation value breaks the extra U(1) symmetry. In the simplest scenario with just one pair of singlet fields and under the assumption of L-R symmetry one obtains quark mass matrices {\it \`a la Fritzsch}. The U(1) symmetry can be made anomaly free by the Green-Schwarz mechanism in which case the canonical unification of the gauge couplings emerges as its byproduct. The generation of neutrino masses requires either two extra heavy scalar (Higgs) fields to determine the texture structure of the righthanded neutrino mass matrix or the latter will contain a hierarchy of scales
Topics in chaotic dynamics

Various kinematical quantities associated with the statistical properties of
dynamical systems are examined: statistics of the motion, dynamical bases and
Lyapunov exponents. Markov partitons for chaotic systems, without any attempt
at describing ``optimal results''. The Ruelle principle is illustrated via its
relation with the theory of gases. An example of an application predicts the
results of an experiment along the lines of Evans, Cohen, Morriss' work on
viscosity fluctuations. A sequence of mathematically oriented problems
discusses the details of the main abstract ergodic theorems guiding to a proof
of Oseledec's theorem for the Lyapunov exponents and products of random
matricesComment: Plain TeX; compile twice; 30 pages; 140K Keywords: chaos,
  nonequilibrium ensembles, Markov partitions, Ruelle principle, Lyapunov
  exponents, random matrices, gaussian thermostats, ergodic theory, billiards,
  conductivity, gas.
On Renormalization Group Flows and Polymer Algebras

In this talk methods for a rigorous control of the renormalization group (RG)
flow of field theories are discussed. The RG equations involve the flow of an
infinite number of local partition functions. By the method of exact
beta-function the RG equations are reduced to flow equations of a finite number
of coupling constants. Generating functions of Greens functions are expressed
by polymer activities. Polymer activities are useful for solving the large
volume and large field problem in field theory. The RG flow of the polymer
activities is studied by the introduction of polymer algebras. The definition
of products and recursive functions replaces cluster expansion techniques.
Norms of these products and recursive functions are basic tools and simplify a
RG analysis for field theories. The methods will be discussed at examples of
the $\Phi^4$-model, the $O(N)$ $\sigma$-model and hierarchical scalar field
theory (infrared fixed points).Comment: 32 pages, LaTeX, MS-TPI-94-12, Talk presented at the conference
  ``Constructive Results in Field Theory, Statistical Mechanics and Condensed
  Matter Physics'', 25-27 July 1994, Palaiseau, Franc
Renormalizing Partial Differential Equations

In this review paper, we explain how to apply Renormalization Group ideas to
the analysis of the long-time asymptotics of solutions of partial differential
equations. We illustrate the method on several examples of nonlinear parabolic
equations. We discuss many applications, including the stability of profiles
and fronts in the Ginzburg-Landau equation, anomalous scaling laws in
reaction-diffusion equations, and the shape of a solution near a blow-up point.Comment: 34 pages, Latex; bricmont@fyma.ucl.ac.be; ajkupiai@cc.helsinki.f
Equivalence of the Euclidean and Wightman Field Theories

The new inversion formula for the Laplace transformation of the tempered
distributions with supports in the closed positive semiaxis is obtained. The
inverse Laplace transform of the tempered distribution is defined by means of
the limit of the special distribution constructed from this distribution. The
weak spectral condition on the Euclidean Green's functions requires that some
of the limits needed for the inversion formula exist for any Euclidean Green's
function with even number of variables. We prove that the initial
Osterwalder--Schrader axioms (1973) and the weak spectral condition are
equivalent with the Wightman axioms.Comment: 26 pages, LATEX, SMI - 94 - 17
A terminological interpretation of (abductive) logic programming

The logic program formalism is commonly viewed as a modal or default logic. In this paper, we propose an alternative interpretation of the formalism as a terminological logic. A terminological logic is designed to represent two different forms of knowledge. A TBox represents definitions for a set of concepts. An ABox represents the assertional knowledge of the expert. In our interpretation, a logic program is a TBox providing definitions for all predicates; this interpretation is present already in Clark's completion semantics. We extend the logic program formalism such that some predicates can be left undefined and use classical logic as the language for the ABox. The resulting logic can be seen as an alternative interpretation of abductive logic program formalism. We study the expressivity of the formalism for representing uncertainty by proposing solutions for problems in temporal reasoning, with null values and open domain knowledge.status: publishe
Stochastic aggregation model for the multifractal distribution of matter

Two main features of the observable distribution of visible matter are the space correlations of galaxy positions and the mass function of galaxies. As discussed in Pietronero and Sylos Labini on this issue ([1], see also [2],[3]), the concept of multifractal (MF) distribution (including the masses) naturally unifies these two properties. Hence with the knowledge of the whole MF spectrum one obtains information on the correlations in space as well as on the mass function. From a theoretical point of view one would like to identify the dynamical process that leads to such a MF distribution. In order to gain some insight into this complex problem we have developed a simple stochastic model that includes some of the basic properties of aggregation process and allows us to pose a variety of interesting question concerning the possible dynamical origin of the MF distribution. The dynamics is characterised by some parameters, that have a direct physical meaning in term of cosmological processes. In this way we can relate the input parameters of the dynamics to the properties of the final configuration and produce a sort of phase diagram
The Theory of Everything vs the Theory of Anything

To what extent can our limited set of observations be used to pin down the
specifics of a ``Theory of Everything''? In the limit where the links are
arbitrarily tenuous, a ``Theory of Everything'' might become a ``Theory of
Anything''. A clear understanding of what we can and can not expect to learn
about the universe is particularly important in the field of particle
cosmology. The aim of this article is to draw attention to some key issues
which arise in this context, in the hopes of fostering further discussion. In
particular, I explore the idea that a variety of different inflaton potentials
may contribute to worlds ``like ours''. A careful examination of the
conditional probability questions we can ask might give a physical measure of
what is ``natural'' for an inflation potential which is quite different from
those previously used.Comment: 13 pages plain LaTeX, no figures. To appear in the proceedings of
  ``The Birth of the Universe and Fundamental Forces'', Rome, May 1994, F.
  Occhionero Editor, Springer Verlag. Imperial/TP/93-94/56 REVISED 10/94: Minor
  improvements, more referneces, no major change
A Schrodinger Equation for Quantum Universes

We discuss how to fix the gauge in the canonical treatment of Lagrangians,
with finite number of degrees of freedom, endowed with time reparametrization
invariance. The motion can then be described by an effective Hamiltonian acting
on the gauge shell canonical space. The system is then suited for quantization.
We apply this treatment to the case of a Robertson--Walker metric interacting
with zero modes of bosonic fields and write a \S equation for the on--shell
wave function (Presented at the International Workshop ``Birth of the Universe
and Fundamental Physics'', Rome, May 18-21, 1994).Comment: 4 pages, POSTSCRIPT fil
Ionization of Rydberg atoms in a low frequency field: modelling by maps
  of transition to chaotic behavior

We investigate a microwave ionization of highly excited atom in a low
frequency field and show that such a process may be studied on the bases of map
for the electron energy change during the period of the electron motion between
two subsequent passages at aphelion. Simple approximate criterion results to
the threshold field for transition to chaotic behavior very close to the
numerical results. We show that transition from adiabatic to chaotic ionization
mechanism takes place when the field frequency to the electron's Kepler
frequency ration approximately equals 0.1.Comment: 5 pages, LaTEX, 37Kb, 2 figures (compressed and uuencoded PostScript)
  included in text. To be published in Chaos: The interplay between
  stochastics, classics and quanta, Ed. by P. Garbaczewski, et al. Lecture
  notes in Physics, 1995
Some notes on power management on FPGA-based systems

The final publication is available at Springer via http://dx.doi.org/10.1007/3-540-60294-1_108Although the energy required to perform a logic operation has continuously dropped at least by ten orders of magnitude since early vacuum-tube electronics [1], the increasing clock frequency and gate density of the current integrated circuits has appended power consumption to traditional design trade-offs. This paper explore the usefullness of some low-power design methods based on architectural and implementation modifications, for FPGA-based electronic systems. The contribution of spurious transitions to the overal consumption is evidenced and main strategies for its reduction are analized. The efectiveness of pipelining and partitioning inprovements as low-power design methodologies are quantified by case-studies based on array multipliers. Moreover, a methodology suitable for FPGAs power analysis is presented.This work has been supported by the CICYT of Spain under contract TIC92-0083. The authors wish to thank Seamus McQuaid for his constructive comment
A compact data structure and parallel algorithms for permutation graphs

The original publication is available at www.springerlink.comInternational audienceStarting from a permutation of {0,...,n-1} we compute in parallel with a workload of O(n log n) a compact data structure of size O(n log n). This data structure allows to obtain the associated permutation graph and the transitive closure and reduction of the associated order of dimension 2 efficiently. The parallel algorithms obtained have a workload of O(n + m log n) where m is the number of edges of the permutation graph. They run in time O(log^2 n) on a CREW PRA
From parallel comparability graph recognition and modular decomposition

The original publication is available at www.springerlink.com : Parallel comparability graph recognition and modular decompositionInternational audienceA parallelization of the algorithm of Golumbic for recognizing comparability graphs is proposed for the concurrent parallel random access machine (CRCW PRAM). Parallel algorithms for finding a transitive orientation and the modular decomposition of any undirected graph are deduced from an extension of the theory of Golumbic toward modular decomposition. The algorithms for recognizing and transitively orienting comparability graphs run in O(log n) time using d m processors and the modular decomposition algorithm runs in O(log n) time using n^3 processors (n, m and d respectively denote the number of vertices, the number of edges and the maximal degree of the undirected input graph)
Positive Unit Hyperresolution Tableaux and Their Application to Minimal Model Generation

Minimal Herbrand models of sets of first-order clauses are useful in several areas of computer science, e.g. automated theorem proving, program verification, logic programming, databases, and artificial intelligence. In most cases, the conventional model generation algorithms are
inappropriate because they generate nonminimal Herbrand models and can
be inefficient. This article describes an approach for generating the minimal
Herbrand models of sets of first-order clauses. The approach builds upon
positive unit hyperresolution (PUHR) tableaux, that are in general smaller
than conventional tableaux. PUHR tableaux formalize the approach initially introduced with the theorem prover SATCHMO. Two minimal model generation procedures are described. The first one expands PUHR tableaux
depth-first relying on a complement splitting expansion rule and on a form
of backtracking involving constraints. A Prolog implementation, named
MM-SATCHMO, of this procedure is given and its performance on benchmark suites is reported. The second minimal model generation procedure
performs a breadth-first, constrained expansion of PUHR (complement)
tableaux. Both procedures are optimal in the sense that each minimal model
is constructed only once, and the construction of nonminimal models is interrupted as soon as possible. They are complete in the following sense	
The depth-first minimal model generation procedure computes all minimal
Herbrand models of the considered clauses provided these models are all
finite. The breadth-first minimal model generation procedure computes all
finite minimal Herbrand models of the set of clauses under consideration.
The proposed procedures are compared with related work in terms of both
principles and performance on benchmark problems.
Logic program specialisation: how to be more specific

Standard partial deduction suffers from several drawbacks when
compared to top-down abstract interpretation schemes. Conjunctive
partial deduction, an extension of standard partial deduction,
remedies one of those, namely the lack of side-ways information
passing. But two other problems remain: the lack of
success-propagation as well as the lack of inference of global
success-information. We illustrate these drawbacks and show how they
can be remedied by combining conjunctive partial deduction with an
abstract interpretation technique known as more specific program
construction. We present a simple, as well as a more refined
integration of these methods. Finally we illustrate the practical
relevance of this approach for some advanced applications, like
proving functionality or specialising certain meta-programs written in
the ground representation, where it surpasses the precision of current
abstract interpretation techniques.status: publishe
A cyclic distributed garbage collector for network objects

This paper presents an algorithm for distributed garbage collection and outlines its implementation within the Network Objects system. The algorithm is based on a reference listing scheme, which is augmented by partial tracing in order to collect distributed garbage cycles. Processes may be dynamically organised into groups, according to appropriate heuristics, to reclaim distributed garbage cycles. The algorithm places no overhead on local collectors and suspends local mutators only briefly. Partial tracing of the distributed graph involves only objects thought to be part of a garbage cycle: no collaboration with other processes is required. The algorithm offers considerable flexibility, allowing expediency and fault-tolerance to be traded against completeness
A natural deduction approach to dynamic logic

Natural Deduction style presentations of program logics are useful in view of the implementation of such logics in interactive proof development environments, based on type theory, such as LEGO, Coq, etc. In fact, ND-style systems are the kind of systems which can take best advantage of the possibility of reasoning "under assumptions" offered by proof assistants generated by Logical Frameworks. In this paper we introduce and discuss sound and complete proof systems in Natural Deduction style for representing various "truth" consequence relations of Dynamic Logic. We discuss the design decisions which lead to adequate encodings of these logics in Coq. We derive in Dynamic Logic a set of rules representing a ND-style system for Hoare Logic
An interactive system for drawing graphs

Abstract: In spite of great advances in the automatic drawing of medium and large graphs, the tools available for drawing small graphs exquisitely (that is, with the aesthetics commonly found in professional publications and presentations) are still very primitive. Commercial tools, e.g., Claris Draw, provide minimal support for aesthetic graph layout. At the other extreme, research prototypes based on constraint methods are overly general for graph drawing. Our system improves on general constraint-based approaches to drawing and layout by supporting only a small set of “macro” constraints that are specifically suited to graph drawing. These constraints are enforced by a generalized spring algorithm. The result is a usable and useful tool for drawing small graphs easily and nicely.Engineering and Applied Science
Games and Weak-Head Reduction for Classical PCF

« The original publication is available at www.springerlink.com »International audienceWe present a game model for classical PCF, a finite version of PCF extended by a catch/throw mechanism. This model is built from E-dialogues, a kind of two-players game defined by Lorenzen. In the E-dialogues for classical PCF, the strategies of the first player are isomorphic to the Böhm trees of the language. We define an interaction in E-dialogues and show that it models the weak-head reduction in classical PCF. The interaction is a variant of Coquand's debate and the weak-head reduction is a variant of the reduction in Krivine's Abstract Machine. We then extend E-dialogues to a kind of games similar to Hyland-Ong's games. Interaction in these games also models weak-head reduction. In the intuitionistic case (i.e. without the catch/throw mechanism), the extended E-dialogues are Hyland-Ong's games where the innocence condition on strategies is now a rule. Our model for classical PCF is different from Ong's model of Parigot's lambda-mu-calculus. His model works by adding new moves to the intuitionistic case while ours works by relaxing the game rules
Redundant argument filtering of logic programs

Revised version of the official proceedingsThis paper is concerned with the problem of removing, from a given
logic program, {\em redundant arguments}. These are arguments which
can be removed without affecting correctness. Most program
specialisation techniques, even though they perform argument filtering
and redundant clause removal, fail to remove a substantial number of
redundant arguments, yielding in some cases rather inefficient
residual programs. We formalise the notion of a redundant argument and
show that one cannot decide effectively whether a given argument is
redundant. We then give a safe, effective approximation of the notion
of a redundant argument and describe several simple and efficient
algorithms calculating based on the approximative notion. We conduct
extensive experiments with our algorithms on mechanically generated
programs illustrating the practical benefits of our approach.status: publishe
theta-subsumption for structural matching

Structural matching, originally introduced by Steven Vere, implements and formalizes the notion of a "most specific generalisation" of two productions, possibly in the presence of a background theory. Despite various studies in the mid-seventies and early eighties, several problems remained. These include the use of background knowledge, the nonuniqueness of most specific generalisations, and handling in-equalities. We show how Gordon Plotkin's notions of "least general generalisation" and "relative least general generalisation" defined on clauses can be adapted for use in structural matching such that the remaining problems disappear. Defining clauses as universally quantified disjunctions of literals and productions as existentially quantified conjunctions of literals, it is shown that the lattice on clauses imposed by theta-subsumption is order-isomorphic to the lattice on productions needed for structural matching.status: publishe
Deformable templates for tracking and analysis of intravascular ultrasound sequences

Deformable Template models are first applied to track the inner wall of coronary arteries in intravascular ultrasound sequences, mainly in the assistance to angioplasty surgery. A circular template is used for initializing an elliptical deformable model to track wall deformation when inflating a balloon placed at the tip of the catheter. We define a new energy function for driving the behavior of the template and we test its robustness both in real and synthetic images. Finally we introduce a framework for learning and recognizing spatio-temporal geometric constraints based on Principal Component Analysis (eigenconstraints)
Refining interval temporal logic specifications

Interval Temporal Logic (ITL) was designed as a tool for the specification and verification of systems. The development of an executable subset of ITL, namely Tempura, was an important step in the use of temporal logic as it enables the developer to check, debug and simulate the design. However, a design methodology is missing that transforms an abstract ITL specification to an executable (concrete) Tempura program. The paper describes a development technique for ITL based on refinement calculus. The technique allows the development to proceed from high level “abstract” system specification to low level “concrete” implementation via a series of correctness preserving refinement steps. It also permits a mixture of abstract specification and concrete implementation at any development step. To allow the development of such a technique, ITL is extended to include modularity, resources and explicit communication. This allows synchronous, asynchronous and shared variable concurrency to be explicitly expressed. These constructs also help in solving the problems, like lack of expressing modularity, timing and communication, discovered during the use of ITL and Tempura for a large-scale application.Funded by EPSRC Research Grant GR/K25922: A compositional approach to the specification of systems using ITL and Tempura