Showing papers by "École Normale Supérieure published in 1989"
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TL;DR: In this paper, the Curry-Howard isomorphism and the normalisation theorem of a natural deduction system T coherence spaces have been studied in the context of linear logic and linear logic semantics.
Abstract: Sense, denotation and semantics natural deduction the Curry-Howard isomorphism the normalisation theorem Godel's system T coherence spaces denotational semantics of T sums in natural deduction system F coherence semantics of the sum cut elimination (Hauptsatz) strong normalisation for F representation theorem semantics of System F what is linear logic?
1,771 citations
TL;DR: An unexpected topographical resemblance between adenylyl cyclase and various plasma membrane channels and transporters was observed, which suggests possible, unappreciated functions for this important enzyme.
Abstract: Complementary DNA's that encode an adenylyl cyclase were isolated from a bovine brain library. Most of the deduced amino acid sequence of 1134 residues is divisible into two alternating sets of hydrophobic and hydrophilic domains. Each of the two large hydrophobic domains appears to contain six transmembrane spans. Each of the two large hydrophilic domains contains a sequence that is homologous to a single cytoplasmic domain of several guanylyl cyclases; these sequences may represent nucleotide binding sites. An unexpected topographical resemblance between adenylyl cyclase and various plasma membrane channels and transporters was observed. This structural complexity suggests possible, unappreciated functions for this important enzyme.
718 citations
TL;DR: The problem of image reconstruction and restoration is first formulated, and some of the current regularization approaches used to solve the problem are described, and a Bayesian interpretation of the regularization techniques is given.
Abstract: Developments in the theory of image reconstruction and restoration over the past 20 or 30 years are outlined. Particular attention is paid to common estimation structures and to practical problems not properly solved yet. The problem of image reconstruction and restoration is first formulated. Some of the current regularization approaches used to solve the problem are then described. The concepts of a priori information and compound criterion are introduced. A Bayesian interpretation of the regularization techniques is given which clarifies the role of the tuning parameters and indicates how they could be estimated. The practical aspects of computing the solution, first when the hyperparameters are known and second when they must be estimated, are then considered. Conclusions are drawn, and points that still need to be investigated are outlined. >
716 citations
TL;DR: In this paper, rare earth element concentrations have been measured in hydrothermal solutions from geothermal fields in Italy, Dominica, Valles Caldera, Salton Sea and the Mid-Atlantic Ridge.
586 citations
01 Dec 1989
TL;DR: The λ&sgr;-calculus is a refinement of the λ-Calculus where substitutions are manipulated explicitly, and provides a setting for studying the theory of substitutions, with pleasant mathematical properties.
Abstract: The ls-calculus is a refinement of the l-calculus where substitutions are manipulated explicitly. The ls-calculus provides a setting for studying the theory of substitutions, with pleasant mathematical properties. It is also a useful bridge between the classical l-calculus and concrete implementations.
577 citations
01 Sep 1989
TL;DR: A probabilistic algorithm can be used to discover words of small weight in a linear binary code, which is asymptotically quite large but can be applied for codes of a medium size.
Abstract: We describe a probabilistic algorithm, which can be used to discover words of small weight in a linear binary code. The work-factor of the algorithm is asymptotically quite large but the method can be applied for codes of a medium size. Typical instances that are investigated are codewords of weight 20 in a code of length 300 and dimension 150.
507 citations
TL;DR: In this paper, a capillary type model with wall effect corrections is proposed to determine the pressure drop through packed beds of parallelepipedal particles, where the tortuosity factor and the dynamic specific surface area are used as mean structure parameters.
456 citations
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TL;DR: A new kind of programming language, with the following features: a simple graph rewriting semantics, a complete symmetry between constructors and destructors, and a type discipline for deterministic and deadlock-free (microscopic) parallelism.
Abstract: We propose a new kind of programming language, with the following features:a simple graph rewriting semantics,a complete symmetry between constructors and destructors,a type discipline for deterministic and deadlock-free (microscopic) parallelism.Interaction nets generalize Girard's proof nets of linear logic and illustrate the advantage of an integrated logic approach, as opposed to the external one. In other words, we did not try to design a logic describing the behaviour of some given computational system, but a programming language for which the type discipline is already (almost) a logic.In fact, we shall scarcely refer to logic, because we adopt a naive and pragmatic style. A typical application we have in mind for this language is the design of interactive softwares such as editors or window managers.
391 citations
TL;DR: It is found that it is usually an excellent approximation to assume that intrasubband and/or intrawell relaxations are faster than intersubband and interwell ones.
Abstract: We report on calculations of scattering times for electrons in single or multiple quantum wells subjected to a longitudinal electric field. Static scatterers (Coulombic impurities and interface defects) as well as acoustical or optical phonons are considered. Intrasubband and intersubband contributions in single quantum wells as well as the intrawell and interwell ones in multiple quantum wells are analyzed and compared. We find that it is usually an excellent approximation to assume that intrasubband and/or intrawell relaxations are faster than intersubband and interwell ones. The variations of the relaxation times upon the strength of an electric field applied along the growth axis make evident the part played by the polarization of the carrier wave function.
373 citations
TL;DR: This work studies via simulation how a lattice breaks if each bond is an elastic beam having longitudinal and flexural breaking thresholds randomly selected according to various probability distributions.
Abstract: We study via simulation how a lattice breaks if each bond is an elastic beam having longitudinal and flexural breaking thresholds randomly selected according to various probability distributions. We observe scaling of force, displacement, and number of broken beams in the controlled regime. The distribution of local forces just before breaking is characterized by a multifractal spectrum f(\ensuremath{\alpha}).
336 citations
TL;DR: In this article, a study of the mechanical behavior of thermally cracked granites indicated a negative Poisson ratio in compression and tension, and it is most probable that the stresses which remained in the material during cooling caused these abnormalities.
TL;DR: In this article, it was shown that a thin film with small dynamic contact angle and driven by an external body force is unstable to the formation of fingers in the direction perpendicular to the main flow.
Abstract: We show that a thin film with small dynamic contact angle and driven by an external body force is unstable to the formation of fingers in the direction perpendicular to the main flow. The instability is largest in the capillary region near the contact line, where the force due to surface tension is comparable to the viscous and gravitational forces. The fastest growing wavelength is calculated in the limit of small-amplitude disturbances. These instabilities may be related to finger patterns observed in gravitational flows and spinning drops.
TL;DR: An investigation is conducted of the high-rate punctured convolutional codes suitable for Viterbi and sequential decoding of known short-memory codes.
Abstract: An investigation is conducted of the high-rate punctured convolutional codes suitable for Viterbi and sequential decoding. Results on known short-memory codes M >
TL;DR: It is shown that theoretical models of magnetically disordered materials (spin glasses) provide a new class of error-correction codes that can, under certain circumstances, constitute the first known codes to saturate Shannon's well-known cost-performance bounds.
Abstract: DURING the transmission of information, errors may occur because of the presence of noise, such as thermal noise in electronic signals or interference with other sources of radiation. One wants to recover the information with the minimum error possible. In theory this is possible by increasing the power of the emitter source. But as the cost is proportional to the energy fed into the channel, it costs less to code the message before sending it, thus including redundant 'coding' bits, and to decode at the end. Coding theory provides rigorous bounds on the cost-effectiveness of any code. The explicit codes proposed so far for practical applications do not saturate these bounds; that is, they do not achieve optimal cost-efficiency. Here we show that theoretical models of magnetically disordered materials (spin glasses) provide a new class of error-correction codes. Their cost performance can be calculated using the methods of statistical mechanics, and is found to be excellent. These models can, under certain circumstances, constitute the first known codes to saturate Shannon's well-known cost-performance bounds.
TL;DR: Tetrahymanol has been identified in several sediment samples from different depositional environments by gas chromatography-mass spectrometry and by coinjections with an authentic standard as mentioned in this paper.
TL;DR: In this article, two simplified microstructural models that account for permeability and conductivity of low-porosity rocks are compared, both of which result from statistics and percolation theory.
Abstract: Two simplified microstructural models that account for permeability and conductivity of low-porosity rocks are compared. Both models result from statistics and percolation theory. The first model assumes that transport results from the connection of 1D objects or “pipes”; the second model assumes that transport results from the connection of 2D objects or “cracks.” In both cases, statistical methods permit calculation of permeability k and conductivity σ, which are dependent on three independent microvariables: average pipe (crack) length, average pipe radius (crack aperture), and average pipe (crack) spacing. The degree of connection is one aspect of percolation theory. Results show that use of the mathematical concept of percolation and use of the rock physics concept of tortuosity are equivalent. Percolation is used to discuss k and σ near the threshold where these parameters vanish. Relations between bulk parameters (permeability, conductivity, porosity) are calculated and discussed in terms of microvariables.
01 Jul 1989
TL;DR: A new sampling method for the calculation of form-factors is presented, which is an alternative to the hemi-cube technique introduced by Cohen and Greenberg for radiosity calculations and is particularly well suited to the extended form- Factors calculation.
Abstract: We analyse some recent approaches to the global illumination problem by introducing the corresponding reflection operators, and we demonstrate the advantages of a two-pass method. A generalization of the system introduced by Wallace et al. at Siggraph '87 to integrate diffuse as well as specular effects is presented. It is based on the calculation of extended form-factors, which allows arbitrary geometries to be used in the scene description, as well as refraction effects. We also present a new sampling method for the calculation of form-factors, which is an alternative to the hemi-cube technique introduced by Cohen and Greenberg for radiosity calculations. This method is particularly well suited to the extended form-factors calculation. The problem of interactive display of the picture being created is also addressed by using hardware-assisted projections and image composition to recreate a complete specular view of the scene.
TL;DR: In this article, the authors discuss superstring models with spontaneous breaking of N = 1, 2 or 4 space-time supersymmetry via coordinate-dependent compactifications from five to four dimensions.
TL;DR: This method avoids explicitly computing such a function and instead produces values only at the grid points and is equivalent to the Briggs method for two-dimensional regular grids.
Abstract: Interpolation of a function ƒ (.) known at some data points of RP is a common problem. Many computer applications (e.g., automatic contouring) need to perform interpolation only at the nodes of a given grid. Whereas most classical methods solve the problem by finding a function defined everywhere, the proposed method avoids explicitly computing such a function and instead produces values only at the grid points. For two-dimensional regular grids, a special case of this method is identical to the Briggs method (see “Machine Contouring Using Minimum Curvature,” Geophysics 17, 1 (1974)), while another special case is equivalent to a discrete version of thin plate splines (see J. Duchon, Fonctions Splines du type Plaque Mince en Dimention 2, Seminaire d'analyse numerique, n 231, U.S.M.G., Grenoble, 1975; and J. Enriquez, J. Thomann, and M. Goupillot, Application of bidimensional spline functions to geophysics, Geophysics 48, 9 (1983)).
TL;DR: In this article, the problem of transforming a nonlinear multi-input system into a linear controllable one via nonsingular dynamic feedback and (extended) state space diffeomorphism is addressed.
TL;DR: Wide variations were found in the optical and physical properties of the films, even among films produced by nominally the same deposition techniques.
Abstract: Fourteen university, government, and industrial laboratories prepared a total of twenty pairs of single-layer titanium dioxide films. Several laboratories analyzed the coatings to determine their optical properties, thickness, surface roughness, absorption, wetting contact angle, and crystalline structure. Wide variations were found in the optical and physical properties of the films, even among films produced by nominally the same deposition techniques.
TL;DR: In this paper, the authors study the number of unbiased random patterns which can be stored in a neural network of N neurons used as an associative memory, in the case where the synaptic efficacies are constrained to take the values ± 1.
Abstract: We study the number p of unbiased random patterns which can be stored in a neural network of N neurons used as an associative memory, in the case where the synaptic efficacies are constrained to take the values ±1. We find a solution with one step of replica symmetry breaking a la Parisi. This solution gives a critical capacity α c =p/N ∼ 0.83 which seems to agree with known numerical results Nous etudions le nombre p de prototypes aleatoires non biaises qui peuvent etre memorises dans un reseau de N neurones utilise comme memoire associative, dans le cas ou les efficacites synaptiques ne peuvent prendre que les valeurs ±1. Nous trouvons une solution avec une etape de brisure de symetrie des repliques a la Parisi. Cette solution predit une capacite optimale α c =p/N∼0,83 qui semble en bon accord avec les resultats numeriques connus
TL;DR: In this article, the authors describe a family of stochastic location-routing problems which consist of simultaneously locating a depot among a set of potential sites, determining the vehicle fleet size and designing collection routes through customers having random supplies.
TL;DR: In this paper, it is shown that on short time scales each element of the soap film moves as a whole so that the film can be considered as a two-dimensional fluid with a local density proportional to its thickness.
TL;DR: In this paper, a set of reconstructions of the Western Pacific marginal basins between 56 Ma and the present at key periods (56, 43, 32, 20, 12 and 3 Ma) are presented.
TL;DR: A low density of vacancies in a 2D, spin-1/2, Heisenberg antiferromagnet leads to a metallic phase with incommensurateAntiferromagnetic order, i.e., with the staggered magnetization rotating in a plane with the wave number proportional to the density.
Abstract: A low density of vacancies in a 2D, spin-1/2, Heisenberg antiferromagnet leads (for a range of effective couplings) to a metallic phase with incommensurate antiferromagnetic order, i.e., with the staggered magnetization rotating in a plane with the wave number proportional to the density. This structure originates from the polarization of the antiferromagnetic dipole moments of the vacancies. The excitation spectrum of this spiral state includes an interesting low-lying mode. Implications for neutron scattering and normal-state resistivity are discussed.
TL;DR: In this paper, a combined study of river and atmospheric fluxes has been carried out, where it is shown that the atmospheric input of red dust is of the same order of magnitude as the annual downstream flow of rivers discharging to the Western Mediterranean.
TL;DR: In this article, a general approach to the problem of determination of elastoplastic properties of metallic polycrystals at finite transformations is presented. But the authors focus on the case of granular media for which the elastic tangent moduli may be considered piecewise constant.
TL;DR: In this article, treatment of methyl 5-acetamido with thiophenol, phenylmethanethiol, and ethanethylamine in the presence of boron trifluoride etherate gave the corresponding 2-thio-β-glycosides 3−5.