Optimal majority rules and quantitative Condorcet properties of setwise Kemeny voting schemes

The important Kemeny problem, which consists of computing median consensus rankings of an election with respect to the Kemeny voting rule, admits important applications in biology and computational social choice and was generalized recently via an interesting setwise approach by Gilbert et. al. Our first results establish optimal quantitative extensions of the Unanimity property and the well-known $3/4$-majority rule of Betzler et al. for the classical Kemeny median problem. Moreover, by elaborating an exhaustive list of quantified axiomatic properties (such as the Condorcet and Smith criteria, the $5/6$-majority rule, etc.) of the $3$-wise Kemeny rule where not only pairwise comparisons but also the discordance between the winners of subsets of three candidates are also taken into account, we come to the conclusion that the $3$-wise Kemeny voting scheme induced by the $3$-wise Kendall-tau distance presents interesting advantages in comparison with the classical Kemeny rule. For example, it satisfies several improved manipulation-proof properties. Since the $3$-wise Kemeny problem is NP-hard, our results also provide some of the first useful space reduction techniques by determining the relative orders of pairs of alternatives. Our works suggest similar interesting properties of higher setwise Kemeny voting schemes which justify and compensate for the more expensive computational cost than the classical Kemeny scheme

Comparing RNA structures using a full set of biologically relevant edit operations is intractable

7 pagesArc-annotated sequences are useful for representing structural information of RNAs and have been extensively used for comparing RNA structures in both terms of sequence and structural similarities. Among the many paradigms referring to arc-annotated sequences and RNA structures comparison (see \cite{IGMA_BliDenDul08} for more details), the most important one is the general edit distance. The problem of computing an edit distance between two non-crossing arc-annotated sequences was introduced in \cite{Evans99}. The introduced model uses edit operations that involve either single letters or pairs of letters (never considered separately) and is solvable in polynomial-time \cite{ZhangShasha:1989}. To account for other possible RNA structural evolutionary events, new edit operations, allowing to consider either silmutaneously or separately letters of a pair were introduced in \cite{jiangli}; unfortunately at the cost of computational tractability. It has been proved that comparing two RNA secondary structures using a full set of biologically relevant edit operations is {\sf\bf NP}-complete. Nevertheless, in \cite{DBLP:conf/spire/GuignonCH05}, the authors have used a strong combinatorial restriction in order to compare two RNA stem-loops with a full set of biologically relevant edit operations; which have allowed them to design a polynomial-time and space algorithm for comparing general secondary RNA structures. In this paper we will prove theoretically that comparing two RNA structures using a full set of biologically relevant edit operations cannot be done without strong combinatorial restrictions

Nearest constrained circular words

In this paper, we study circular words arising in the development of equipment using shields in brachytherapy. This equipment has physical constraints that have to be taken into consideration. From an algorithmic point of view, the problem can be formulated as follows: Given a circular word, find a constrained circular word of the same length such that the Manhattan distance between these two words is minimal. We show that we can solve this problem in pseudo polynomial time (polynomial time in practice) using dynamic programming

Étude comparative de l’intégration scolaire chez des adolescents suicidaires et non suicidaires victimes de carence d’attention parentale

Cette recherche fait l'analyse de l'intégration scolaire d'un échantillon de 150 adolescents victimes de carence d'attention parentale. On y compare un groupe de 78 suicidaires à un groupe de 72 non-suicidaires. Les adolescents sont âgés de 14 à 17 ans et sont recrutés dans six écoles de la région montréalaise. Les suicidaires n'éprouvent pas plus de problèmes de discipline, d'absentéisme, de rendement scolaire ou de vie de groupe à l'école que les non-suicidaires. Cependant, ils semblent moins motivés à l'école que les non-suicidaires puisqu'ils arrivent plus fréquemment en retard en classe. Ils s'engagent aussi dans un moins grand nombre d'activités parascolaires offertes par l'école et vivent plus de relations conflictuelles avec les adultes de l'école que les non-suicidaires. En outre, les suicidaires cumulent plus de caractéristiques reliées à l'abandon des études que les non-suicidaires. En conclusion, les différences observées au niveau de l'intégration scolaire font ressortir quelques indices de vulnérabilité associés aux comportements suicidaires à l'adolescence lorsqu'il y a carence d'attention parentale.This research analyzes school integration of a sample of 150 adolescents lacking parental attention. A group of 78 suicidal students is compared to a group of 72 non-suicidals. Students are 14 to 17 years old and are recruited in six schools of the Montreal region. Suicidal adolescents do not experience more problems of discipline, absenteeism, academic performance or relationship with their peers than non suicidal adolescents. However they appear less motivated in school than non suicidal adolescents being more frequently late in class. They also participate less in extracurricular activities offered by the school and experience more conflicts with the school's adults than non-suicidals. Moreover, suicidal adolescents have more characteristics related to dropping out than non suicidais. Finally, the differences observed regarding school integration highlight some signs of vulnerability associated with suicidal behaviour during adolescence when they lack parental attention

Structure familiale, relations parents-enfants et conduites suicidaires à l’école secondaire

Une enquête portant sur 2 327 élèves de niveau secondaire III, IV et V de la région de Montréal montre que les suicidaires comptent pour 13,2% de cet échantillon, et que 6,7% avouent avoir tenté de se suicider. Le taux de suicidaires est plus élevé chez les filles que chez les garçons, et il est moins élevé dans les écoles où la proportion d'allophones est supérieure à 50%. La séparation ou le divorce des parents et la négligence du père sont deux facteurs qui contribuent en soi à l'augmentation du taux de suicidaires. Par contre, le décès du père ou de là mère n'est pas un facteur qui y contribue. Le taux de suicidaires est à son niveau le plus élevé quand il y a un parent substitut. Il existe, d'autre part un effet d'interaction entre la scolarité du père et la structure familiale. Chez les élèves dont la famille est intacte, on dénombre moins de sujets suicidaires si le père est plus scolarisé que s'il est moins scolarisé; on ne retrouve plus cette différence si la famille est séparée. Par contre, on dénote plus de séparations chez les parents plus scolarisés. En ce qui concerne le plus haut taux de suicidaires chez les filles, celui-ci ne s'explique pas entièrement par une moins bonne relation avec les parents. Un indice laisse entendre cependant qu'un conflit avec les parents pourrait perturber les filles plus que les garçons. Enfin, si les problèmes de santé grave sont associés à un taux plus élevé de suicidaires, ce lien est relativement indépendant de la qualité de la relation avec les parents.A study made on a sample of 2,327 Montréal area students of third, fourth and fifth year of High School shows that suicidal behaviors ("les suicidaires") account for 13.2 % of youth interrogated, and that 6.7 % admit to having attempted suicide. The suicidal behavior rate is higher among girls than boys and it is lower in schools where the proportion of allophones is over 50 %. The separation of parents and the father's negligence are factors that contribute to raising the rate of suicidal behavior. However, a deceased father or mother has no effect on the rate. The rate of suicidal behavior is at its highest when there is a substitute parent. A relation exists, however, between a father's level of scolarity and the family structure. When students come from an unbroken home, there are fewer suicidal subjects when the father has a high rather than a low level of scolarity ; this difference disappears when the family is separated. However, the authors have noticed a greater rate of separation among parents with a higher level of scolarity. As for the higher rate of suicidal behaviors among girls, it is not entirely connected to poor parent-child relations. The data suggest to the authors that parent conflicts could possibly perturb girls more than boys. And finally, although serious health problems are associated to a higher rate of suicidal behavior, this link is relatively indépendant of the quality of parent-child relations

Écologie de la famille, réseau social et comportements suicidaires en milieu scolaire

Ce texte résume une recherche menée dans des écoles de Montréal en 1987 et 1988 sur l'écologie familiale et le réseau social en rapport avec les tendances suicidaires sérieuses chez des adolescents. Les deux groupes analysés comprennent 78 suicidaires et 72 non-suicidaires interviewés individuellement. Tous les sujets présentent un score élevé de manque d'attention de la part d'au moins un des deux parents. Les résultats indiquent que les parents des suicidaires se séparent moins souvent de façon définitive que le groupe de comparaison, mais que les familles des suicidaires vivent plus de changements de structure familiale après un premier bris. Il n'y a pas de différences importantes en ce qui concerne les déménagements, que ce soit en nombre ou en distance. Par ailleurs, les deux groupes nomment un nombre similaire de personnes importantes, obtiennent autant de soutien de divers types et rapportent autant de conflits. Mais, dans l'ensemble de ces comparaisons, les suicidaires nomment proportionnellement plus d'adultes. Nous faisons l'hypothèse que le taux plus élevé de séparation parentale chez les non-suicidaires peut représenter un facteur de protection plutôt que de vulnérabilité tel qu'on le propose habituellement. En ce qui a trait au réseau social, le fait que les suicidaires s'orientent un peu plus vers les adultes pourrait nuire à la socialisation avec leurs pairs et, conséquemment, à leur intégration sociale.This article sums up the outcome of a research project conducted in Montréal schools in 1987 and 1988, and focusing on how family ecology and social networks relate to strong suicidal tendencies among teenagers. Two groups were involved in the study: one with 78 suicidal persons, the other with 72 non-suicidal persons. Teenagers in each group were interviewed separately. All subjects reported high lack of attention from at least one of the two parents. Results also show that parents of suicidal teens experience permanent break-ups less frequently in comparison to the other group. However, families of suicidal teens tend to experience deeper changes in the structure of the family unit following an initial separation. With respect to moving, there are no significant differences, whether in the number of moves or the important people, have access to as many different kinds of support and report the same number of conflicts. In all these comparisons, however, suicidal teenagers do name a proportionately higher number of adults. This leads the authors to hypothesize that a higher rate of parental separation among non-suicidal teens could represent a protective factor rather than a vulnerability factor, as is usually suggested. In terms of social networks, the fact that suicidal teens seek out adults to a greater degree could impede on their socializing with peers and, therefore, on their social integration

Median of an odd number of permutations

International audienceGiven m permutations π1, π2 . . . πm of {1, 2, . . . , n} and a distance function d, the median problem is to find a permutation π ∗ that is the "closest" of the m given permutations. Here, we study the problem under the Kendall-τ distance that counts the number of pairwise disagreements between permutations. This problem is also known, in the context of rank aggregation, as the Kemeny Score Problem and has been proved to be NP-hard when m ≥ 4. This article is an extension of [4], where some nice combinatorial properties of the case m = 3 where stated without proof, to the general case m ≥ 3, m odd

Analysing Anti-patterns Static Relationships with Design Patterns

Anti-patterns are motifs that are usually thought to be good solutions tosome design or implementation problems, but back-fires badly when applied. Previousstudies have reported that anti-patterns make object oriented systems hard tomaintain. Anti-patterns motifs usually have dependencies with other classes in thesystem. In this paper, we propose to analyse these dependencies (with in particulardesign patterns) in order to understand how developers can maintain programscontaining anti-patterns. To the best of our knowledge, no substantial investigationof anti-pattern dependencies with design patterns has been done before. This paperpresents the results of a study that we performed on three different systems, ArgoUML,JFreeChart, and XercesJ, written in Java, and of size ranges from 1,191to 3,325 classes, to analyse the static relationships between anti-patterns and designpatterns. We found that these relationships (1) exist, but (2) are temporaryand (3) classes participating in such relationships are more change-prone but lessfault-prone than other anti-pattern classes

Modeling RNA tertiary structure motifs by graph-grammars

A new approach, graph-grammars, to encode RNA tertiary structure patterns is introduced and exemplified with the classical sarcin–ricin motif. The sarcin–ricin motif is found in the stem of the crucial ribosomal loop E (also referred to as the sarcin–ricin loop), which is sensitive to the α-sarcin and ricin toxins. Here, we generate a graph-grammar for the sarcin-ricin motif and apply it to derive putative sequences that would fold in this motif. The biological relevance of the derived sequences is confirmed by a comparison with those found in known sarcin–ricin sites in an alignment of over 800 bacterial 23S ribosomal RNAs. The comparison raised alternative alignments in few sarcin–ricin sites, which were assessed using tertiary structure predictions and 3D modeling. The sarcin–ricin motif graph-grammar was built with indivisible nucleotide interaction cycles that were recently observed in structured RNAs. A comparison of the sequences and 3D structures of each cycle that constitute the sarcin–ricin motif gave us additional insights about RNA sequence–structure relationships. In particular, this analysis revealed the sequence space of an RNA motif depends on a structural context that goes beyond the single base pairing and base-stacking interactions

Contributions individuelles d’étudiants en formation initiale à l’enseignement des sciences à la construction d’un discours autour d’un thème intégrateur

Notre étude présente comment deux professeures ont créé une zone de convergence entre deux cours obligatoires au baccalauréat à l’enseignement secondaire au Québec. Afin de favoriser une démarche de développement professionnel ancrée dans une perspective socioconstructiviste, les étudiants ont travaillé en collaboration à concevoir des situations d’apprentissage en laboratoire qui tiennent compte des concepts étudiés dans leurs cours de gestion de classe (intervention pédagogique) et dans leur cours de didactique des sciences. Nous présentons la démarche pédagogique mise en place dans les deux cours de même que le discours collaboratif co-construit par les étudiants durant la session de l’automne 2011. Nos résultats démontrent la pertinence d’une telle démarche sur la capacité des étudiants à avoir un discours argumenté au plan théorique dans la création de situations de laboratoire et les liens possibles dans la gestion des interactions en classe.Our study shows how two professors created a zone of convergence between two compulsory courses in the Bachelor of Secondary Education program in Quebec. In order to promote a process of professional development rooted in a socioconstructivist perspective, the students worked collaboratively to develop laboratory learning situations that incorporated the concepts studied in their classroom management course and their science education course. We present the pedagogical approach implemented in the two courses as well as the collaborative discourse co-constructed by the students during the Fall 2011 semester. Our results demonstrate the relevance of such an approach for supporting students' ability to engage in a well-argued theoretical discourse on creating laboratory situations and the possible links with the management of classroom interactions