In this paper a FPGA implementation of a novel neural stochastic model for solving constrained NP-hard problems is proposed and developed. The model exploits pseudo-boolean functions both to express the constraints an...
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In this paper a FPGA implementation of a novel neural stochastic model for solving constrained NP-hard problems is proposed and developed. The model exploits pseudo-boolean functions both to express the constraints and to define the cost function, interpreted as energy of a neural network. A wide variety of NP-hard problems falls in the class of problems that can be solved by this model, particularly those having a quadratic pseudo-boolean penalty function. The proposed hardware implementation provides high computation speed by exploiting parallelism, as the neuron update and the constraint violation check can be performed in parallel over the whole network. The neural system has been tested on random and benchmark graphs, showing good performance with respect to the same heuristic for the same problems. Furthermore, the computational speed of the FPGA implementation has been measured and compared to software implementation. The developed architecture featured dramatically faster computation, with respect to the software implementation, even adopting a low-cost FPGA chip. (C) 2008 Elsevier Ltd. All rights reserved.
The Sugeno integral, for a given fuzzy measure, is studied under the viewpoint of aggregation. In particular, we give some equivalent expressions of it. We also give an axiomatic characterization of the class of all t...
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The Sugeno integral, for a given fuzzy measure, is studied under the viewpoint of aggregation. In particular, we give some equivalent expressions of it. We also give an axiomatic characterization of the class of all the Sugeno integrals. Some particular subclasses, such as the weighted maximum and minimum functions are investigated as well. (C) 2000 Elsevier Science B.V. All rights reserved.
We investigate the computational power of max-min propagation (MMP) neural networks, composed of neurons with maximum (Max) or minimum (Min) activation functions, applied over the weighted sums of inputs. The main res...
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We investigate the computational power of max-min propagation (MMP) neural networks, composed of neurons with maximum (Max) or minimum (Min) activation functions, applied over the weighted sums of inputs. The main results presented are that a single-layer MMP network can represent exactly any pseudo-boolean function F: {0;1}(n) --> [0;1], and that two-layer MMP neural networks are universal approximators. In addition, it is shown that several well-known fuzzy min-max (FMM) neural networks, such as Simpson's FMM, are representable by MMP neural networks.
Factored Edge-Valued Binary Decision Diagrams form an extension to Edge-Valued Binary Decision Diagrams. By associating both an additive and a multiplicative weight with the edges, FEVBDDs can be used to represent a w...
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Factored Edge-Valued Binary Decision Diagrams form an extension to Edge-Valued Binary Decision Diagrams. By associating both an additive and a multiplicative weight with the edges, FEVBDDs can be used to represent a wider range of functions concisely. As a result, the computational complexity for certain operations can be significantly reduced compared to EVBDDs. Additionally, the introduction of multiplicative edge weights allows us to directly represent the so-called complement edges which are used in OBDDs, thus providing a one to one mapping of all OBDDs to FEVBDDs. Applications such as integer linear programming and logic verification that have been proposed for EVBDDs also benefit from the extension. We also present a complete matrix package based on FEVBDDs and apply the package to the problem of solving the Chapman-Kolmogorov equations.
Very large nonlinear unconstrained binary optimization problems arise in a broad array of applications. Several exact or heuristic techniques have proved quite successful for solving many of these problems when the ob...
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Very large nonlinear unconstrained binary optimization problems arise in a broad array of applications. Several exact or heuristic techniques have proved quite successful for solving many of these problems when the objective function is a quadratic polynomial. However, no similarly efficient methods are available for the higher degree case. Since high degree objectives are becoming increasingly important in certain application areas, such as computer vision, various techniques have been recently developed to reduce the general case to the quadratic one, at the cost of increasing the number of variables by introducing additional auxiliary variables. In this paper we initiate a systematic study of these quadratization approaches. We provide tight lower and upper bounds on the number of auxiliary variables needed in the worst-case for general objective functions, for bounded-degree functions, and for a restricted class of quadratizations. Our upper bounds are constructive, thus yielding new quadratization procedures. Finally, we completely characterize all "minimal" quadratizations of negative monomials.
We propose prior distributions for all parts of the specification of a Markov mesh model. In the formulation, we define priors for the sequential neighborhood, for the parametric form of the conditional distributions ...
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We propose prior distributions for all parts of the specification of a Markov mesh model. In the formulation, we define priors for the sequential neighborhood, for the parametric form of the conditional distributions and for the parameter values. By simulating from the resulting posterior distribution when conditioning on an observed scene, we thereby obtain an automatic model selection procedure for Markov mesh models. To sample from such a posterior distribution, we construct a reversible jump Markov chain Monte Carlo algorithm (RJMCMC). We demonstrate the usefulness of our prior formulation and the limitations of our RJMCMC algorithm in two examples.
Discrete Markov random fields form a natural class of models to represent images and spatial datasets. The use of such models is, however, hampered by a computationally intractable normalising constant. This makes par...
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Discrete Markov random fields form a natural class of models to represent images and spatial datasets. The use of such models is, however, hampered by a computationally intractable normalising constant. This makes parameter estimation and a fully Bayesian treatment of discrete Markov random fields difficult. We apply approximation theory for pseudo-boolean functions to binary Markov random fields and construct approximations and upper and lower bounds for the associated computationally intractable normalising constant. As a by-product of this process we also get a partially ordered Markov model approximation of the binary Markov random field. We present numerical examples with both the pairwise interaction Ising model and with higher-order interaction models, showing the quality of our approximations and bounds. We also present simulation examples and one real data example demonstrating how the approximations and bounds can be applied for parameter estimation and to handle a fully Bayesian model computationally.
This paper investigates the complexity of various recognition problems for pseudo-boolean functions (i.e., real-valued functions defined on the unit hypercubeB n = {0, 1} n ), when such functions are represented as ...
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This paper investigates the complexity of various recognition problems for pseudo-boolean functions (i.e., real-valued functions defined on the unit hypercubeB n = {0, 1} n ), when such functions are represented as multilinear polynomials in their variables. Determining whether a pseudo-boolean function (a) is monotonic, or (b) is supermodular, or (c) is threshold, or (d) has a unique local maximum in each face ofB n , or (e) has a unique local maximum inB n , is shown to be NP-hard. A polynomial-time recognition algorithm is presented for unimodular functions, previously introduced by Hansen and Simeone as a class of functions whose maximization overB n is reducible to a network minimum cut problem.
In this paper we present a new data structure called Edge-Valued Binary-Decision Diagrams (EVBDD). An EVBDD is a directed acyclic graph, that provides a canonical and compact representation of functions that involve b...
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In this paper we present a new data structure called Edge-Valued Binary-Decision Diagrams (EVBDD). An EVBDD is a directed acyclic graph, that provides a canonical and compact representation of functions that involve both boolean and integer quantities. In general, EVBDDS provide a more versatile and powerful representation that Ordinary Binary Decision Diagrams. We first describe the structure and properties of EVBDDS, and present a general algorithm for performing a variety of binary operations. Next, we describe an important extension of EVBDDS, called Structural EVBDDS, and show how they can be used for hierarchical verification.
Many bodies around the world make their decisions through voting systems in which voters have several options and the collective result also has several options. Many of these voting systems are anonymous, i.e., all v...
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Many bodies around the world make their decisions through voting systems in which voters have several options and the collective result also has several options. Many of these voting systems are anonymous, i.e., all voters have an identical role in voting. Anonymous simple voting games, a binary vote for voters and a binary collective decision, can be represented by an easy weighted game, i.e., by means of a quota and an identical weight for the voters. Widely used voting systems of this type are the majority and the unanimity decision rules. In this article, we analyze the case in which voters have two or more voting options and the collective result of the vote has also two or more options. We prove that anonymity implies being representable through a weighted game if and only if the voting options for voters are binary. As a consequence of this result, several significant enumerations are obtained.
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