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Results for criterions: Topic: Approximation Modify search criterions Results n° 1 to 8 of 23 matches Page 1 . 2 . 3 . >> Next page Title A new general explanation of Bendford's law Author GAUVRIT Nicolas, DELAHAYE Jean-Paul Keywords Benford's law, Equiprobability bias, Paradoxe Topics Approximation, Number theory, Probabilities Abstract According to Benford's law, the first digit of a random number does not follow a uniform distribution, as many people believe, but a logarithmic distribution. This law was at the begining purely experimental, but it is now established that it holds for various mathematical series and some natural data sets. Concerning data sets, Benford's law often appears as a good approximation of the reality, but as no more than an approximation. Our aim is to present a new explanation for this law. We argue that it should not be considered as a mathematical paradox, but as a purely psycholo-gical paradox, a result of a cognitive bias. We express a general criterion of regularity on a random variable X and prove that, whenever X follow this criterion, X is approximately Benford. Number 182, Summer 2008 Language   French Read the article Title Solving aggregation of preferences problems using doubly stochastic matrix approximation Author TAKOUDA Pawoumodom-L. Keywords Aggregation of preferences, Alternating projection, Doubly stochastic matrices, Permutation matrice Topics Approximation, Linear Algebra, Numerical Analysis, Permutations, Social Choice Abstract In this work, we consider the classical problem of aggregation of preferences. We extend a previous work by Blin [5]. Under some assumptions, he formulated this problem as that of finding the nearest permutation matrix to a doubly stochastic matrix (called normalized of the agreement matrix, which collects the information contained in the expressed individual preferences). We reduce these assumptions, and we introduce a two-phase scheme for solving the problem. The first phase consists in approximating the matrix that contains the individual preferences information (which looses here the doubly stochastic character) by a doubly stochastic matrix using an algorithm proposed by the author [20 in a previous work. We thereby reduce the more general problem to that considered by Blin, which can be solved by using linear programming or, more directly, as a weighted bipartite matching problem. Number 161, Spring 2003, special issue: Operations research and decision aid Language   French Read the article Title Vijay V. Vazirani, "Approximation algorithms", Berlin-Heidelberg, Springer-Verlag, 2001 Author HUDRY Olivier Keywords None Topics Book review, Algorithms - Algorithmic Theory, Approximation, Computer Sciences Abstract Book review Number 161, Spring 2003, special issue: Operations research and decision aid Language   French Read the article Title Genesis of a theory Author FREY Louis Keywords Approximation, Architecture of Antiquity, Divisions of a line segment, Pell-Fermat equation, Various means Topics Approximation, Archeology, Arithmetic - Number Theory, Geometry, History of sciences, Modelling Abstract A mathematical (here, specifically arithmetical) theory is presented to explain many observed proportions in monuments of the ancient Greek and Roman civilizations. Number 156, Winter 2001 Language   French Read the article Title Tree adjustments for partial distances Author GUENOCHE Alain, GRANDCOLAS Stéphane Keywords Partial distance, Sequential method, Tree reconstruction Topics Algorithms - Algorithmic Theory, Approximation, Classification - Clustering - Partitioning, Distances, Orders and preorders, Trees Abstract In tree clustering, we try to approximate a given dissimilarity matrice by a tree distance. In some cases, especially when comparing biological séquences, some dissimilarity values cannot be evaluated and we get some partial dissimilarity with undefined values. In that case one can develop a sequential method to reconstruct a valued tree or evaluate the missing values using a tree model. This paper introduces two methods of this kind and compare them simulating noisy partial tree dissimilarities. Number 146, Summer 1999 Language   French Read the article Title Nominal harmonic analysis applied to individual trajectories typology Author BARBARY Olivier, PINZON SARMIENTO Luz-Mary Keywords None Topics Approximation, Data Analysis, Demography, Sociology, Stochastic Processes, Time Series Abstract The article aims at a theoretical and practical presentation «nonominal harmonic analysis» as a tool for descriptive statistic of categorical stochastic processes and its application to human mobility studies. The first part is a mathematical overview of the extension of scalar spectral analysis to a categorical process and how it can be approximate by a particular kind of correspondences analysis based on times that individuals accumulate in the process states. The second and third parts deal with application to a data set taken from a survey on residential mobility in Bogota metropolitan area. We found the method able to provide an interesting typology of urban residential trajectories and to show some relationships between residential mobility and other biographical variables like family events and professional changes. Number 144, Winter 1998 Language   French Read the article Title Quasi-sets and approximations of r-ordered partitions Author SERFATI Michel Keywords None Topics Approximation, Classification - Clustering - Partitioning, Discrete Mathematics, Distances, Lattices, Orders and preorders Abstract From a mathematical viewpoint, the theory of r-ordered repartitions deals with some extension of the concept of "power set", by the mean of a complete distributive lattice. As to interpretaiton, one may consider each r-repartition as the exhaustive distribution of some character (or quality) to all the elements of some set ü, according to r viewpoints, the viewpoints forming a chain (linearly ordered set). This paper deals uniquely with the establishing of some distance d on the set pr(ü) of all the r-repartitions of ü, and also of the approximation of any given r-ordered partition P by the subsets of ü which are the nearest from P, according to the metric d. Any of these subsets may then be considered as convenient for replacing P, and one may interpret this replacement as the result of some terminal decision. Number 143, Fall 1998 Language   French Read the article Title Discrete straight lines and calendars Author TROESCH Albert Keywords None Topics Algorithms - Algorithmic Theory, Approximation, Arithmetic - Number Theory Abstract The structure of a calendar can be described by a sequence of quasi-affine forms. Such a sequence, that will be called quasi-affine basis, generalizes the notion of numeration basis. The problem of the date conversion is therefore reduced to the writing of the Julian Day in such a basis. A discrete straight line recognizing algorithm enables us to obtain the good quasi-affine basis. As examples are given the julian, gregorian, islamic and judaic calendars. Number 141, Spring 1998 Language   French Read the article Page 1 . 2 . 3 . >> Next page Users rights : The entire journal is licensed under a Creative Commons license