A Trichotomy for Regular Trail Queries

Regular path queries (RPQs) are an essential component of graph query languages. Such queries consider a regular expression r and a directed edge-labeled graph G and search for paths in G for which the sequence of labels is in the language of r. In order to avoid having to consider infinitely many paths, some database engines restrict such paths to be trails, that is, they only consider paths without repeated edges. In this paper we consider the evaluation problem for RPQs under trail semantics, in the case where the expression is fixed. We show that, in this setting, there exists a trichotomy. More precisely, the complexity of RPQ evaluation divides the regular languages into the finite languages, the class T_tract (for which the problem is tractable), and the rest. Interestingly, the tractable class in the trichotomy is larger than for the trichotomy for simple paths, discovered by Bagan et al. [Bagan et al., 2013]. In addition to this trichotomy result, we also study characterizations of the tractable class, its expressivity, the recognition problem, closure properties, and show how the decision problem can be extended to the enumeration problem, which is relevant to practice

Evaluation and Enumeration Problems for Regular Path Queries

Regular path queries (RPQs) are a central component of graph databases. We investigate decision- and enumeration problems concerning the evaluation of RPQs under several semantics that have recently been considered: arbitrary paths, shortest paths, and simple paths. Whereas arbitrary and shortest paths can be enumerated in polynomial delay, the situation is much more intricate for simple paths. For instance, already the question if a given graph contains a simple path of a certain length has cases with highly non-trivial solutions and cases that are long-standing open problems. We study RPQ evaluation for simple paths from a parameterized complexity perspective and define a class of simple transitive expressions that is prominent in practice and for which we can prove a dichotomy for the evaluation problem. We observe that, even though simple path semantics is intractable for RPQs in general, it is feasible for the vast majority of RPQs that are used in practice. At the heart of our study on simple paths is a result of independent interest: the two disjoint paths problem in directed graphs is W[1]-hard if parameterized by the length of one of the two paths

Containment of Simple Regular Path Queries

Testing containment of queries is a fundamental reasoning task in knowledge representation. We study here the containment problem for Conjunctive Regular Path Queries (CRPQs), a navigational query language extensively used in ontology and graph database querying. While it is known that containment of CRPQs is expspace-complete in general, we focus here on severely restricted fragments, which are known to be highly relevant in practice according to several recent studies. We obtain a detailed overview of the complexity of the containment problem, depending on the features used in the regular expressions of the queries, with completeness results for np, pitwo, pspace or expspace

Le contrat social: Un outil d'analyse pour les pays de la région Moyen-Orient et Afrique du Nord (MENA), et au-delà

Le contrat social est un concept clé des sciences sociales portant sur les relations entre l'État et la société. Il renvoie à l'en-semble des accords explicites ou implicites intervenant entre tous les groupes sociaux concernés et le souverain (c.-à-d. le gouvernement ou tout autre acteur au pouvoir), définissant leurs droits et obligations mutuels (Loewe & Zintl, à paraître). L'analyse des contrats sociaux permet de mieux comprendre : (i) pourquoi certains groupes sociaux sont mieux positionnés que d'autres sur les plans social, politique ou économique, (ii) pourquoi certains se révoltent et revendiquent un nouveau contrat social et, par conséquent, (iii) ce qui peut amener un pays à sombrer dans un conflit violent. En outre, le concept montre en quoi les interventions étrangères peuvent influer sur les relations entre l'État et la société en renforçant la position du souverain ou celle de groupes sociaux donnés. Il montre que l'inclusion insuffisante de certains groupes peut provoquer une fragilité de l'État, des déplacements et des migrations. Cependant, jusqu'à présent, aucune définition convenable ni aucune expression concrète n'ont encore été données au terme "contrat social" - au détriment de la recherche et de la coopération internationale. Ce type d'approche analytique structurée des relations entre l'État et la société est impératif, tant dans la recherche que dans la politique, dans la région MENA et au-delà. Le présent document d'information définit un cadre, suggérant une analyse de (i) la portée des contrats sociaux, (ii) leur substance et (iii) leur dimension temporelle. Après l'indépendance, les gouvernements de la région MENA ont établi un type de contrat social spécifique avec les citoyens, essentiellement basé sur la redistribution des rentes. Ils ont permis aux citoyens d'accéder à l'énergie et aux denrées alimentaires à prix subventionnés, à une éducation publique gratuite et à des emplois dans la fonction publique, en contrepartie de la reconnaissance tacite de la légitimité des régimes politiques, et ce malgré un manque de participation politique. Mais face à la croissance démographique et à la baisse des recettes publiques, certains gouvernements n'ont plus pu s'acquitter de leurs obligations et ont concentré leurs dépenses sur des groupes d'importance stratégique, subordonnant l'octroi de ressources à l'assentiment politique. Les soulèvements de 2011 dans de nombreux pays arabes expriment alors une insatisfaction profonde vis-à-vis des contrats sociaux qui n'assuraient plus ni la participation à la vie politique, ni l'octroi d'avantages sociaux substantiels (au moins pour une grande partie de la population). À la suite, les pays de la région MENA ont pris des directions différentes. La Tunisie a déjà avancé vers un dé-veloppement plus inclusif et une participation politique accrue. Le Maroc et la Jordanie essaient de rétablir certains volets de leur ancien contrat social, sur la base d'un modèle paternaliste, sans participation substantielle. Dans le contrat social émergeant en Égypte, le gouvernement ne promet pas plus que la sécurité individuelle et collective, et uniquement en contrepartie d'un assentiment politique total. La Libye, le Yémen et la Syrie sont tombés dans la guerre civile sans qu'aucun nouveau contrat ne se dessine au niveau national, et l'Irak se bat pour en établir un. Et les mouvements de fuite et de migration affectent également les contrats sociaux de pays voisins comme la Jordanie, la Turquie et le Liban. Tous les pays de la région MENA devront œuvrer à la mise en place de nouveaux contrats sociaux aux fins de réduire l'instabilité actuelle et favoriser leur reconstruction physique. Le présent document propose un point sur la dimension conceptuelle de la renégociation de ces contrats et leur importance pour la coopération internationale avec ces pays

The social contract: An analytical tool for countries in the Middle East and North Africa (MENA) and beyond

The social contract is a key concept in social science literature focusing on state-society relations. It refers to the "entirety of explicit or implicit agreements between all relevant societal groups and the sovereign (i.e. the government or any other actor in power), defining their rights and obligations towards each other" (Loewe & Zintl, forthcoming). The analysis of social contracts helps the understanding of: (i) why some societal groups are socially, politically or economically better off than others, (ii) why some revolt and demand a new social contract and, thus, (iii) why a country descends into violent conflict. In addition, the concept shows how foreign interventions and international co-operation may affect state-society relations by strengthening the position of the state or of specific societal groups. It illustrates that state fragility, displacement and migration can arise from social contracts becoming less inclusive. Nevertheless, the term "social contract" has so far been neither well defined nor operationalised - to the detriment of both research and of bi- and multilateral co-operation. Such a structured analytical approach to state-society relations is badly needed both in research and in politics, in particular but not exclusively for the analysis of MENA countries. This briefing paper sets the frame, suggesting a close analysis of (i) the scope of social contracts, (ii) their substance and (iii) their temporal dimension. After independence, MENA governments established a specific kind of social contract with citizens, mainly based on the redistribution of rents from natural resources, development aid and other forms of transfers. They provided subsidised food and energy, free public education and government jobs to citizens in compensation for the tacit recognition of political regimes' legitimacy despite a lack of political participation. But with growing populations and declining state revenues, some governments lost their ability to fulfil their duties and focused spending on strategically important social groups, increasingly tying resource provision to political acquiescence. The uprisings that took place in many Arab countries in 2011 can be seen as an expression of deep dissatisfaction with social contracts that no longer provided either political participation or substantial social benefits (at least for large parts of the population). After the uprisings, MENA countries developed in different directions. While Tunisia is a fair way towards more inclusive development and political participation, Morocco and Jordan are trying to restore some parts of the former social contract, providing for paternalistic distribution without substantial participation. In Egypt's emerging social contract, the government promises little more than individual and collective security, and that only under the condition of full political acquiescence. Libya, Yemen and Syria have fallen into civil wars with no countrywide new contract in sight, and Iraq has been struggling for one since 2003. In addition, flight and migration also affect the social contracts of neighbouring countries such as Jordan, Turkey, and Lebanon. All MENA countries are designing, or will need to design, new social contracts in order to reduce the current instability and enable physical reconstruction. This briefing paper informs on the status of conceptual considerations of social contract renegotiation in MENA countries and its meaning for international co-operation with them

Der Gesellschaftsvertrag: Ein Analyseinstrument nicht nur für Länder im Nahen Osten und in Nordafrika (MENA)

Der Gesellschaftsvertrag ist ein Schlüsselbegriff in der sozialwissenschaftlichen Literatur, der auf die Beziehungen zwischen Staat und Gesellschaft fokussiert. Er bezeichnet die Gesamtheit expliziter oder impliziter Vereinbarungen zwischen allen relevanten gesellschaftlichen Gruppen und dem Souverän (d.h. der Regierung oder einem anderen Machthaber) über wechselseitige Rechte und Pflichten (Loewe & Zintl, forthcoming). Die Analyse von Gesellschaftsverträgen verdeutlicht u.a. (i) warum einige Gesellschaftsgruppen sozial, politisch oder wirtschaftlich besser gestellt sind als andere, (ii) warum es Revolten und Forderungen nach neuen Gesellschaftsverträgen gibt, (iii) warum also manche Länder in Gewaltkonflikte abgleiten. Zudem zeigt das Konzept, dass externe Akteure die Beziehungen zwischen Staat und Gesellschaft beeinflussen können, indem sie die Regierung oder bestimmte Gesellschaftsgruppen stärken. Und es verdeutlicht, dass staatliche Fragilität, Flucht und Migration daraus resultieren können, dass Gesellschaftsverträge weniger inklusiv geworden sind. Trotzdem ist der Begriff Gesellschaftsvertrag bisher weder klar definiert noch operationalisiert worden - zum Nachteil von Forschung Politik. Ein strukturierter Ansatz zur Analyse der Beziehungen zwischen Staat und Gesellschaft ist überfällig, v.a. im Hinblick auf die MENA-Länder. Im vorliegenden Papier schlagen wir einen Analyserahmen, der auf (i) Geltungsbereich, (ii) Inhalt und (iii) zeitliche Dimension von Gesellschaftsverträgen fokussiert. Nach Erreichen der Unabhängigkeit schlossen die MENA-Regierungen sehr spezifische Gesellschaftsverträge mit ihren Bürgern, die auf der Umverteilung von Renteneinnahmen aus natürlichen Ressourcen, Entwicklungshilfegeldern und anderen Transfers basierten. Sie versorgten die Bürger mit Lebensmittel- und Energiesubventionen, kostenloser Bildung sowie Jobs im öffentlichen Dienst im Gegenzug dafür, dass diese die Legitimität der Regierungen anerkannten, obwohl es fast keine politische Partizipation gab. Aufgrund von wachsender Bevölkerung und sinkenden Staatseinnahmen konnten die Regierungen ihre Aufgaben aber immer weniger erfüllen. Daher konzentrierten sie ihre Ausgaben immer stärker auf strategisch wichtige Gesellschaftsgruppen und machten sie verstärkt von politischer Zustimmung abhängig. Die Aufstände, die sich 2011 in vielen arabischen Ländern ereigneten, können so auch als Ausdruck tiefer Unzufriedenheit mit den damaligen Gesellschaftsverträgen verstanden werden, die keine politische Partizipation, für große Teile der Bevölkerung aber auch kaum noch Sozialleistungen vorsahen. Seither entwickelten sich die MENA-Länder in verschiedene Richtungen. Tunesien ist auf gutem Weg zu inklusiver Entwicklung und mehr politischer Partizipation. Marokko und Jordanien versuchen, die alten Gesellschaftsverträge - Ressourcenumverteilung ohne nennenswerte Partizipation - wiederherzustellen. Im neuen Gesellschaftsvertrag Ägyptens verspricht die Regierung wenig mehr als individuelle und kollektive Sicherheit, und auch das nur gegen umfassende politische Zustimmung. In Libyen, dem Jemen und Syrien sind Bürgerkriege ausgebrochen, und es besteht keine Aussicht auf einen neuen landesweiten Gesellschaftsvertrag, um den auch der Irak seit 2003 kämpft. Flucht und Migration beeinträchtigen zudem die Gesellschaftsverträge der Nachbarländer Jordanien, Türkei und Libanon. Alle MENA-Länder entwerfen derzeit neue Gesellschaftsverträge oder sollten dies bald tun, um Stabilisierung bzw. Wiederaufbau zu ermöglichen. Im Folgenden informieren wir über den Stand der konzeptionellen Überlegungen zur Neugestaltung der Gesellschaftsverträge in den MENA-Ländern und deren Bedeutung für die internationale Zusammenarbeit

Efficacy and safety of two neutralising monoclonal antibody therapies, sotrovimab and BRII-196 plus BRII-198, for adults hospitalised with COVID-19 (TICO): a randomised controlled trial

We aimed to assess the efficacy and safety of two neutralising monoclonal antibody therapies (sotrovimab [Vir Biotechnology and GlaxoSmithKline] and BRII-196 plus BRII-198 [Brii Biosciences]) for adults admitted to hospital for COVID-19 (hereafter referred to as hospitalised) with COVID-19. In this multinational, double-blind, randomised, placebo-controlled, clinical trial (Therapeutics for Inpatients with COVID-19 [TICO]), adults (aged ≥18 years) hospitalised with COVID-19 at 43 hospitals in the USA, Denmark, Switzerland, and Poland were recruited. Patients were eligible if they had laboratory-confirmed SARS-CoV-2 infection and COVID-19 symptoms for up to 12 days. Using a web-based application, participants were randomly assigned (2:1:2:1), stratified by trial site pharmacy, to sotrovimab 500 mg, matching placebo for sotrovimab, BRII-196 1000 mg plus BRII-198 1000 mg, or matching placebo for BRII-196 plus BRII-198, in addition to standard of care. Each study product was administered as a single dose given intravenously over 60 min. The concurrent placebo groups were pooled for analyses. The primary outcome was time to sustained clinical recovery, defined as discharge from the hospital to home and remaining at home for 14 consecutive days, up to day 90 after randomisation. Interim futility analyses were based on two seven-category ordinal outcome scales on day 5 that measured pulmonary status and extrapulmonary complications of COVID-19. The safety outcome was a composite of death, serious adverse events, incident organ failure, and serious coinfection up to day 90 after randomisation. Efficacy and safety outcomes were assessed in the modified intention-to-treat population, defined as all patients randomly assigned to treatment who started the study infusion. This study is registered with ClinicalTrials.gov, NCT04501978. Between Dec 16, 2020, and March 1, 2021, 546 patients were enrolled and randomly assigned to sotrovimab (n=184), BRII-196 plus BRII-198 (n=183), or placebo (n=179), of whom 536 received part or all of their assigned study drug (sotrovimab n=182, BRII-196 plus BRII-198 n=176, or placebo n=178; median age of 60 years [IQR 50–72], 228 [43%] patients were female and 308 [57%] were male). At this point, enrolment was halted on the basis of the interim futility analysis. At day 5, neither the sotrovimab group nor the BRII-196 plus BRII-198 group had significantly higher odds of more favourable outcomes than the placebo group on either the pulmonary scale (adjusted odds ratio sotrovimab 1·07 [95% CI 0·74–1·56]; BRII-196 plus BRII-198 0·98 [95% CI 0·67–1·43]) or the pulmonary-plus complications scale (sotrovimab 1·08 [0·74–1·58]; BRII-196 plus BRII-198 1·00 [0·68–1·46]). By day 90, sustained clinical recovery was seen in 151 (85%) patients in the placebo group compared with 160 (88%) in the sotrovimab group (adjusted rate ratio 1·12 [95% CI 0·91–1·37]) and 155 (88%) in the BRII-196 plus BRII-198 group (1·08 [0·88–1·32]). The composite safety outcome up to day 90 was met by 48 (27%) patients in the placebo group, 42 (23%) in the sotrovimab group, and 45 (26%) in the BRII-196 plus BRII-198 group. 13 (7%) patients in the placebo group, 14 (8%) in the sotrovimab group, and 15 (9%) in the BRII-196 plus BRII-198 group died up to day 90. Neither sotrovimab nor BRII-196 plus BRII-198 showed efficacy for improving clinical outcomes among adults hospitalised with COVID-19. US National Institutes of Health and Operation Warp Spee