Trying again to fail-first

For constraint satisfaction problems (CSPs), Haralick and Elliott [1] introduced the Fail-First Principle and defined in it terms of minimizing branch depth. By devising a range of variable ordering heuristics, each in turn trying harder to fail first, Smith and Grant [2] showed that adherence to this strategy does not guarantee reduction in search effort. The present work builds on Smith and Grant. It benefits from the development of a new framework for characterizing heuristic performance that defines two policies, one concerned with enhancing the likelihood of correctly extending a partial solution, the other with minimizing the effort to prove insolubility. The Fail-First Principle can be restated as calling for adherence to the second, fail-first policy, while discounting the other, promise policy. Our work corrects some deficiencies in the work of Smith and Grant, and goes on to confirm their finding that the Fail-First Principle, as originally defined, is insufficient. We then show that adherence to the fail-first policy must be measured in terms of size of insoluble subtrees, not branch depth. We also show that for soluble problems, both policies must be considered in evaluating heuristic performance. Hence, even in its proper form the Fail-First Principle is insufficient. We also show that the “FF” series of heuristics devised by Smith and Grant is a powerful tool for evaluating heuristic performance, including the subtle relations between heuristic features and adherence to a policy

A Hybrid Artificial Bee Colony Algorithm for Graph 3-Coloring

The Artificial Bee Colony (ABC) is the name of an optimization algorithm that was inspired by the intelligent behavior of a honey bee swarm. It is widely recognized as a quick, reliable, and efficient methods for solving optimization problems. This paper proposes a hybrid ABC (HABC) algorithm for graph 3-coloring, which is a well-known discrete optimization problem. The results of HABC are compared with results of the well-known graph coloring algorithms of today, i.e. the Tabucol and Hybrid Evolutionary algorithm (HEA) and results of the traditional evolutionary algorithm with SAW method (EA-SAW). Extensive experimentations has shown that the HABC matched the competitive results of the best graph coloring algorithms, and did better than the traditional heuristics EA-SAW when solving equi-partite, flat, and random generated medium-sized graphs

Le fonctionnement des institutions et le déroulement des carrières dans la colonie de Philippes

This paper deals with the political institutions of the Roman colony of Philippi (province of Macedonia), by studying the way in which the civic magistratures follow one another. This study rests on the analysis of the municipal careers such as they appear in the epigraphical cur- sus honorwn.The aim is to highlight some types of careers which reveal local specificities in the institutions. These results belong to a preliminary study for the publication of the first volume of the Corpus of the Greek and Latin inscriptions of Philippi. In appendix the question of the statute of the pmefedumfabrum through the attestations of this title at Philippi is mentioned.Brelaz Cédric, Rizakis Athanasios. Le fonctionnement des institutions et le déroulement des carrières dans la colonie de Philippes. In: Cahiers du Centre Gustave Glotz, 14, 2003. pp. 155-165

De nouveaux notables dans la colonie de Philippes

Οι συγγραφείς παρουσιάζουν την προκαταρκτική δημοσίευση επτά ανέκδοτων επιγραφών, οι οποίες προέρχονται από τη ρωμαϊκή αποικία των Φιλίππων στην επαρχία της Μακεδονίας. Οι επιγραφές αυτές αποκαλύπτουν νέους τοπικούς προύχοντες, οι οποίοι έδρασαν στην αποικία κατά τη διάρκεια του 1ου και του 2ου αι. μ.Χ. Ανάμεσά τους υπάρχει ένας στρατιώτης από τους Φιλίππους, ο οποίος θήτευσε στις κοόρτεις των νυκτοφυλάκων στη Ρώμη, καθώς και πολλοί δημοτικοί άρχοντες και απελεύθεροι από τους Φιλίππους. Όλες οι επιγραφές που σχετίζονται με τους θεσμούς της αποικίας αλλά και αυτές που αναφέρουν μέλη των τάξεων των συγκλητικών και των ιππέων καθώς και στρατιώτες, θα επαναδημοσιευτούν σύντομα στο πρώτο τεύχος του Corpus des inscriptions grecques et latines de Philippes. H συγκέντρωση του επιγραφικού υλικού, το οποίο σχετίζεται με τη δημοτική και την αυτοκρατορική διοίκηση των Φιλίππων, εμπλουτισμένο με πολυάριθμες ανέκδοτες επιγραφές, θα οδηγήσει στην ανανέωση των γνώσεών μας για την κοινωνική και πολιτική δομή της αποικίας.The authors present the preliminary publication of seven hitherto unpublished inscriptions from the Roman colony at Philippi in the province of Macedonia. These inscriptions make known a number of new notables who were active in the colony during the 1st and 2nd centuries AD. Amongst them is a soldier from Philippi who had pursued a career in the cohortes vigilae in Rome, as well as several municipal magistrates and seviri augusti from Philippi. All the inscriptions connected with the institutions of the colony, and also those mentioning members of the senatorial and equestrian orders and soldiers, will shortly be included in the first volume of the Corpus of Greek and Latin Inscriptions of Philippi. The assembling of the epigraphic material relating to the municipal and imperial administration of Philippi, enriched by numerous unpublished inscriptions, will enable us to renew our acquaintance with the social and political structures of the colony.Les auteurs présentent la publication préliminaire de sept inscriptions inédites provenant de la colonie romaine de Philippes dans la province de Macédoine. Ces inscriptions font connaître de nouveaux notables locaux actifs dans la colonie au cours du Ier et du IIe siècles apr. J.-C. On note parmi eux un soldat originaire de Philippes ayant fait carrière dans les cohortes de vigiles à Rome, ainsi que plusieurs magistrats municipaux et sévirs augustaux philippiens. Toutes les inscriptions ayant trait aux institutions de la colonie, en même temps que celles mentionnant des membres des ordres sénatorial et équestre ainsi que des soldats, seront reprises prochainement dans le premier volume du Corpus des inscriptions grecques et latines de Philippes. Le rassemblement du matériel épigraphique relatif à l'administration municipale et impériale à Philippes, enrichi de nombreux inédits, permettra de renouveler notre connaissance des structures sociales et politiques de la colonie.Brélaz Cédric, Frei-Stolba Regula, Rizakis Athanassios, Zannis Angelos G. De nouveaux notables dans la colonie de Philippes. In: Bulletin de correspondance hellénique. Volume 130, livraison 1, 2006. pp. 519-547

The Dynamics of Dynamic Variable Ordering Heuristics

. It has long been accepted that dynamic variable ordering heuristics outperform static orderings. But just how dynamic are dynamic variable ordering heuristics? This paper examines the behaviour of a number of heuristics, and attempts to measure the entropy of the search process at different depths in the search tree. 1 Introduction Many studies have shown that dynamic variable ordering (dvo [9]) heuristics out perform static variable ordering heuristics. But just how dynamic are dynamic variable ordering heuristics? This might be important because if we discover that some dvo heuristic H 1 results in less search effort than heuristic H 2 and H 1 is more dynamic than H 2 then we might expect that we can make a further improvement by increasing the dynamism of H 1 . Conversely if we discover that H 1 is better and less dynamic then we might plan to make H 1 even more ponderous. But how do we measure the dynamism of a heuristic? To investigate this we first look inside the search proc..