205 research outputs found
Reasoning from Last Conflict(s) in Constraint Programming
International audienceConstraint programming is a popular paradigm to deal with combinatorial problems in arti cial intelligence. Backtracking algorithms, applied to constraint networks, are commonly used but su er from thrashing, i.e. the fact of repeatedly exploring similar subtrees during search. An extensive literature has been devoted to prevent thrashing, often classi ed into look-ahead (constraint propagation and search heuristics) and look-back (intelligent backtracking and learning) approaches. In this paper, we present an original look-ahead approach that allows to guide backtrack search toward sources of conicts and, as a side e ect, to obtain a behavior similar to a backjumping technique. The principle is the following: after each conict, the last assigned variable is selected in priority, so long as the constraint network cannot be made consistent. This allows us to find, following the current partial instantiation from the leaf to the root of the search tree, the culprit decision that prevents the last variable from being assigned. This way of reasoning can easily be grafted to many variations of backtracking algorithms and represents an original mechanism to reduce thrashing. Moreover, we show that this approach can be generalized so as to collect a (small) set of incompatible variables that are together responsible for the last conict. Experiments over a wide range of benchmarks demonstrate the e ectiveness of this approach in both constraint satisfaction and automated arti cial intelligence planning
LE CERTE : Centre de Recherche en Techniques d'Expression
Le CERTE ne prĂ©tend pas se substituer Ă ce qui existe, mais ĂȘtre un lieu de rencontre, de rĂ©flexion, et de discussion critique. Il s'adresse donc Ă tous les chercheurs et formateurs, (quels que soient leur statut, leur lieu d'exercice, leur public, leurs disciplines d'origine) qui souhaitent approfondir la didactique de cette discipline, rĂ©flĂ©chir Ă la signification de son Ă©mergence et aux conditions scientifiques de son dĂ©veloppement. Le CERTE - organise une dizaine de rĂ©unions ouvertes chaq..
Passeport pour la science ouverte - Guide pratique Ă l\u27usage des doctorantes et des doctorants
Le Passeport pour la science ouverte est un guide conçu pour vous accompagner à chaque étape de votre parcours de
recherche, depuis lâĂ©laboration de votre dĂ©marche scientifique jusquâĂ la diffusion de ses rĂ©sultats. Il vous propose une sĂ©rie
de bonnes pratiques et dâoutils directement activables et il sâadresse Ă lâensemble des champs disciplinaires
Science ouverte : CODES ET LOGICIELS
Les ordinateurs sont uniquement capables dâexĂ©cuter des instructions Ă©lĂ©mentaires,
écrites dans un langage machine de bas niveau. Pour exécuter un code source sur un ordinateur, il faut donc :
âą soit le compiler, c\u27est-Ă -dire le traduire au prĂ©alable en un code objet fonctionnellement Ă©quivalent, Ă©crit en langage machine exĂ©cutable sur lâordinateur ;
âą soit lâinterprĂ©ter, câest-Ă -dire le traduire Ă la volĂ©e, au sein dâun environnement
dĂ©diĂ© (interprĂ©teur Python, etc.). Les codes sources destinĂ©s Ă ĂȘtre interprĂ©tĂ©s sont souvent appelĂ©s scripts. Les scripts de petite taille sont parfois appelĂ©s macro-instructions, ou macros
Passeport pour la Science Ouverte
Le Passeport pour la science ouverte est un guide conçu pour accompagner les doctorants Ă chaque Ă©tape de leur parcours de recherche, quel que soit leur champ disciplinaire. Il propose une sĂ©rie de bonnes pratiques et dâoutils directement activables
Policy packages for modal shift and CO2 reduction in Lille, France
This paper proposes different policy scenarios to cut CO2 emissions caused by the urban mobility of passengers. More precisely, we compare the effects of the âdirect toolâ of carbon tax, to a combination of âindirect toolsâ â not originally aimed at reducing CO2 (i.e. congestion charging, parking charges and a reduction in public transport travel time) in terms of CO2 impacts through a change in the modal split. In our model, modal choices depend on individual characteristics, trip features (including the effects of policy tools), and land use at origin and destination zones. Personal âCO2 emissions budgetsâ resulting from the trips observed in the metropolitan area of Lille (France) in 2006 are calculated and compared to the situation related to the different policy scenarios. We find that an increase of 50% in parking charges combined with a cordon toll of âŹ1.20 and a 10% travel time decrease in public transport services (made after recycling toll-revenues) is the winning scenario. The combined effects of all the policy scenarios are superior to their separate effects
Recommended from our members
Factors driving public support for road congestion reduction policies: Congestion charging, free public transport and more roads in Stockholm, Helsinki and Lyon
Based on an across-the-board survey conducted among residents of Stockholm, Helsinki and Lyon, we explore the opinions on three policy measures to combat road congestion: congestion charging, free public transport and building more roads. The support for the two latter policies is substantially higher than the support for congestion charging, which is only supported by a majority in Stockholm. Self-interest is important for the formation of the opinion to all three policies. However, fundamental values and general political views, indicated by four attitudinal factors, are even more important in forming opinions towards the three transport policies. Of all attitudinal factors, the one indicating environmental concern most influences the support for all policies. Equity concerns, however, increase the support for free public transport and opposition to taxation increases the support for building more roads.
Our results further suggest that the opinions towards free public transport and building more roads can be mapped along the leftâright political axis, where Environment and Equity are to the left and Pricing and Taxation are to the right. However, the opinion towards congestion charging cuts right through the political spectrum. The impact of the fundamental values and self-interest variables are similar for Stockholm and Helsinki, indicating that even if experience increases the overall support for charging, it does not change the relative strength of different political arguments to any major extent
Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic
This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic
- âŠ