L'émergence du tourisme dans les territoires de l'Afrique tropicale française (années 1920-1950

L'article examine "l'invention du tourisme" en AOF et en AOF dans les années 1920-1950 en s'intéressant à divers acteurs (voyageurs isolés, entrepreneurs de tourisme, autorités coloniales...)

Sur les facteurs des suites de sturm

RésuméCet article a pour objet l'étude d'une construction associant à toute droite de pente p/q (p et q premiers entre eux et q⩽n) un mot de longueur n sur l'alphabet {0,1}. Nous montrons que nous obtenons par cette construction le langage constitué de tous les facteurs des suites de Sturm. Nous formulons, aprés avoir obtenu une èquation fonctionelle dont la solution est la série génératrice de ce langage, une conjecture reliant cette série génératrice à la fonction d'Euler.AbstractIn this paper, we study a construction which connects to each line with slope p/q (such that gcd(p, q) = 1 and q⩽n) a word of length n over the alphabet {0, 1}. We show that this construction yields the language of all the factors of the sturmian sequences. We first obtain a functional equation whose solution is the generating function of this language, and then we give a conjecture relating this generating function to the Euler function

La correspondance de Robinson-Schensted pour les tableaux oscillants gauches

AbstractWe introduce an analog of the Robinson-Schensted algorithm for skew oscillating tableaux which generalizes the well-known correspondence for standard tableaux. We show that this new algorithm enjoys some of the same properties as the original. In particular, it is still true that replacing a permutation by its inverse exchanges the two output tableaux. These facts permit us to derive a number of identities involving the number of such tableaux

Decomposition algorithms for the tree edit distance problem

AbstractWe study the behavior of dynamic programming methods for the tree edit distance problem, such as [P. Klein, Computing the edit-distance between unrooted ordered trees, in: Proceedings of 6th European Symposium on Algorithms, 1998, p. 91–102; K. Zhang, D. Shasha, SIAM J. Comput. 18 (6) (1989) 1245–1262]. We show that those two algorithms may be described as decomposition strategies. We introduce the general framework of cover strategies, and we provide an exact characterization of the complexity of cover strategies. This analysis allows us to define a new tree edit distance algorithm, that is optimal for cover strategies

Average complexity of the Jiang-Wang-Zhang pairwise tree alignment algorithm and of a RNA secondary structure alignment algorithm

International audienceWe prove that the average complexity of the pairwise ordered tree alignment algo- rithm of Jiang, Wang and Zhang is in O(nm), where n and m stand for the sizes of the two trees, respectively. We show that the same result holds for the aver- age complexity of pairwise comparison of RNA secondary structures, using a set of biologically relevant operations

A geometric version of the Robinson–Schensted correspondence for skew oscillating tableaux

AbstractWe consider an analogue of the Robinson–Schensted correspondence for skew oscillating tableaux and we propose a geometric version of this correspondence, extending similar constructions for standard (Combinatoire et représentation du groupe symétrique, Lecture Notes in Mathematics, Vol. 579, Springer, Berlin, 1977, pp. 29–58) and oscillating tableaux (Formal Power Series and Algebraic Combinatorics, FPSAC’99, Univ. Politecnicà de Catalunya, 1999, pp. 141–152). We deduce from this geometric construction new proofs of some combinatorial properties of this correspondence

Local Similarity Between Quotiented Ordered Trees

International audienceIn this paper we propose a dynamic programming algorithm to evaluate local similarity between ordered quotiented trees using a constrained edit scoring scheme. A quotiented tree is a tree defined with an additional equivalent relation on vertices and such that the quotient graph is also a tree. The core of the method relies on two adaptations of an algorithm proposed by Zhang et al. [K. Zhang, D. Shasha, Simple fast algorithms for the editing distance between trees and related problems (1989) 1245-1262] for comparing ordered rooted trees. After some preliminary definitions and the description of this tree edit algorithm, we propose extensions to globally and locally compare two quotiented trees. This last method allows to find the region in each tree with the highest similarity. Algorithms are currently being used in genomic analysis to evaluate variability between RNA secondary structures

An O(n^3)-Time Algorithm for Tree Edit Distance

The {\em edit distance} between two ordered trees with vertex labels is the minimum cost of transforming one tree into the other by a sequence of elementary operations consisting of deleting and relabeling existing nodes, as well as inserting new nodes. In this paper, we present a worst-case $O(n^3)$-time algorithm for this problem, improving the previous best $O(n^3\log n)$-time algorithm~\cite{Klein}. Our result requires a novel adaptive strategy for deciding how a dynamic program divides into subproblems (which is interesting in its own right), together with a deeper understanding of the previous algorithms for the problem. We also prove the optimality of our algorithm among the family of \emph{decomposition strategy} algorithms--which also includes the previous fastest algorithms--by tightening the known lower bound of $\Omega(n^2\log^2 n)$~\cite{Touzet} to $\Omega(n^3)$, matching our algorithm's running time. Furthermore, we obtain matching upper and lower bounds of $\Theta(n m^2 (1 + \log \frac{n}{m}))$ when the two trees have different sizes $m$ and~$n$, where $m < n$.Comment: 10 pages, 5 figures, 5 .tex files where TED.tex is the main on

“ROC” Chips Readout

International audienceThe OMEGA group at LAL has designed 3 chips for ILC calorimeters: one analog (SPIROC) and one digital (HARDROC) for the hadronic one and also one for the electromagnetic one (SKIROC). The readout and the management of these different chips will be explained. To minimize the lines between the ASICs and the DAQ, the readout is made thanks to 2 lines which are common for all the chips: Data and TransmitOn. As the chips are daisy chained, each chip is talking to the DAQ one after the other. When one chip has finished its readout, it starts the readout of the chip just after. Moreover, during this readout, only the chip which is talking to the DAQ is powered: this is made thanks to the POD (Power On Digital) module in the ASIC. In the ILC mode, readout sequence is active during inter bunch crossing (like ADC conversion). Another chip designed for PMM2 R&D program (PARISROC) integrates a new selective readout: that's mean only hit channels are sent to the DAQ in a complete autonomous mode