Star-topology decoupled state-space search in AI planning and model checking

State-space search is a widely employed concept in many areas of computer science. The well-known state explosion problem, however, imposes a severe limitation to the effective implementation of search in state spaces that are exponential in the size of a compact system description, which captures the state-transition semantics. Decoupled state-space search, decoupled search for short, is a novel approach to tackle the state explosion. It decomposes the system such that the dependencies between components take the form of a star topology with a center and several leaf components. Decoupled search exploits that the leaves in that topology are conditionally independent. Such independence naturally arises in many kinds of factored model representations, where the overall state space results from the product of several system components. In this work, we introduce decoupled search in the context of artificial intelligence planning and formal verification using model checking. Building on common formalisms, we develop the concept of the decoupled state space and prove its correctness with respect to capturing reachability of the underlying model exactly. This allows us to connect decoupled search to any search algorithm, and, important for planning, adapt any heuristic function to the decoupled state representation. Such heuristics then guide the search towards states that satisfy a desired goal condition. In model checking, we address the problems of verifying safety properties, which express system states that must never occur, and liveness properties, that must hold in any infinite system execution. Many approaches have been proposed in the past to tackle the state explosion problem. Most prominently partial-order reduction, symmetry breaking, Petri-net unfolding, and symbolic state representations. Like decoupled search, all of these are capable of exponentially reducing the search effort, either by pruning part of the state space (the former two), or by representing large state sets compactly (the latter two). For all these techniques, we prove that decoupled search can be exponentially more efficient, confirming that it is indeed a novel concept that exploits model properties in a unique way. Given such orthogonality, we combine decoupled search with several complementary methods. Empirically, we show that decoupled search favourably compares to state-of-the-art planners in common algorithmic planning problems using standard benchmarks. In model checking, decoupled search outperforms well-established tools, both in the context of the verification of safety and liveness properties.Die Zustandsraumsuche ist ein weit verbreitetes Konzept in vielen Bereichen der Informatik, deren effektive Anwendung jedoch durch das Problem der Zustandsexplosion deutlich erschwert wird. Die Zustandsexplosion ist dadurch charakterisiert dass kompakte Systemmodelle exponentiell große Zustandsräume beschreiben. Entkoppelte Zustandsraumsuche (entkoppelte Suche) beschreibt einen neuartigen Ansatz der Zustandsexplosion entgegenzuwirken indem die Struktur des Modells, insbesondere die bedingte Unabhängigkeit von Systemkomponenten in einer Sterntopologie, ausgenutzt wird. Diese Unabhängigkeit ergibt sich bei vielen faktorisierten Modellen deren Zustandsraum sich aus dem Produkt mehrerer Komponenten zusammensetzt. In dieser Arbeit wird die entkoppelte Suche in der Planung, als Teil der Künstlichen Intelligenz, und der Verifikation mittels Modellprüfung eingeführt. In etablierten Formalismen wird das Konzept des entkoppelten Zustandsraums entwickelt und dessen Korrektheit bezüglich der exakten Erfassung der Erreichbarkeit von Modellzuständen bewiesen. Dies ermöglicht die Kombination der entkoppelten Suche mit beliebigen Suchalgorithmen. Wichtig für die Planung ist zudem die Nutzung von Heuristiken, die die Suche zu Zuständen führen, die eine gewünschte Zielbedingung erfüllen, mit der entkoppelten Zustandsdarstellung. Im Teil zur Modellprüfung wird die Verifikation von Sicherheits- sowie Lebendigkeitseigenschaften betrachtet, die unerwünschte Zustände, bzw. Eigenschaften, die bei unendlicher Systemausführung gelten müssen, beschreiben. Es existieren diverse Ansätze um die Zustandsexplosion anzugehen. Am bekanntesten sind die Reduktion partieller Ordnung, Symmetriereduktion, Entfaltung von Petri-Netzen und symbolische Suche. Diese können, wie die entkoppelte Suche, den Suchaufwand exponentiell reduzieren. Dies geschieht durch Beschneidung eines Teils des Zustandsraums, oder durch die kompakte Darstellung großer Zustandsmengen. Für diese Verfahren wird bewiesen, dass die entkoppelte Suche exponentiell effizienter sein kann. Dies belegt dass es sich um ein neuartiges Konzept handelt, das sich auf eigene Art der Modelleigenschaften bedient. Auf Basis dieser Beobachtung werden, mit Ausnahme der Entfaltung, Kombinationen mit entkoppelter Suche entwickelt. Empirisch kann die entkoppelte Suche im Vergleich zu modernen Planern zu deutlichen Vorteilen führen. In der Modellprüfung werden, sowohl bei der Überprüfung von Sicherheit-, als auch Lebendigkeitseigenschaften, etablierte Programme übertroffen.Deutsche Forschungsgesellschaft; Star-Topology Decoupled State Space Searc

Nasruddin's key: poverty measurement and the government of marginal populations

This paper considers the role of ‘measurement’ and other forms of poverty knowledge in a context where the nature and direction of global economic growth is creating ‘surplus populations’ suffering various forms of marginalisation in the global economy. It links the development of different forms of poverty knowledge with the ways in which states and non-state agents seek to ‘govern’ poverty and poor populations, and with the ‘biopolitics’ whereby calculations are made about the differential allocation of resources towards different sectors of the global population. The paper argues that addressing the root causes of poverty requires social actors to go beyond the narrow limits of institutionally sanctioned and bureaucratically invested ‘poverty knowledge’ that currently dominate policy thinking. Rather than seeking to understand poverty by measuring the characteristics of members of populations, they should try to understand poverty as an aspect of social relations, and try to come to grips with differential insertion of populations in the fields of force of modern globalised capitalism. Analysis should abandon simple notions of ‘marginalisation, and come to grips with the agency of poor people and the complex relationships between informality, marginality, exclusion and incorporation. Ultimately, however, a more nuanced understanding of the role of poverty knowledge in present day biopolitics does not bring with it any easy answers: rather, it challenges applied social scientists to be more aware of the responsibilities they bear as producers of 'useful' knowledge in a time of increased global instability.Center for Development Research (ZEF), University of Bonn, Germany

The evolution of galaxies in massive clusters

We present a study of the evolution of galaxies in massive X-ray selected clusters across half the age of the Universe. This encompasses galaxies on the red sequence from the Brightest Cluster Galaxy (BCG) to the faint red population. We begin at the tip of the red sequence with an investigation into the near infrared evolution of BCGs since z =1. By comparing the BCG Hubble diagram and near-infrared colour evolution to a set of stellar population and semi-analytic models we constrain the evolution and formation redshift of these massive galaxies. Moving down in luminosity from the BCG, in chapter 3 we study the build up of the red sequence in massive clusters. To achieve this we compare the luminosity functions for red galaxies in a homogeneous sample of ten X-ray luminous clusters at z ~ 0.5 to a similarly selected X-ray cluster sample at z ~ 0.1. We quantify this result by measuring the dwarf to giant ratio to ascertain whether faint galaxies have joined the red sequence over the last 5 Gyr. In chapter 4 we study the evolution of the red sequence slope in massive clusters from z=l to present day. We compare our observed slope evolution to that predicted from semi- analytical models based on the Millennium simulation. We also look for trends between the red sequence slope and other cluster observables, such as X—ray luminosity, to investigate whether this will effect cluster detection methods which search for a colour-magnitude relation. In the final science chapter we present the details of our own cluster detection algorithm. This simple algorithm is based on finding clusters through the near-infrared and optical properties of the red sequence, drawing on our galaxy cluster evolution research. We describe the application of the algorithm to object catalogues from the UKIDSS DXS fields in order to find clusters at z ~ 1. To confirm the presence of the clusters we employ deep multi-object spectroscopy on the photometric members. The clusters found in this study are fed back into the high redshift regime of our galaxy evolution research

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 192

This bibliography lists 247 reports, articles, and other documents introduced into the NASA scientific and technical information system in March 1979

The European Green Deal. An Analysis of how the European Commission promises to Manage Climate Change

Màster de Ciutadania i Drets Humans: Ètica i Política, Facultat Filosofia, Universitat de Barcelona, Curs: 2019-2020, Tutor: José Antonio Estévez AraujoClimate Change is the defining challenge of the 21st century. Measures taken today by politicians, companies, consumers, and society in general will directly influence earth's habitability in the decades to come. Through the complex interaction between GHG emissions, global warming, loss of biodiversity, human health and well-being are at risk. While countries of the global north will proportionally suffer less consequences than those of the global South, the projected damages will still be grave. In recent decades, as a result, environmental protection gained an increasing relevance in international treaties, as well as national policies and legislature

Integrated Production and Distribution planning of perishable goods

Tese de doutoramento. Programa Doutoral em Engenharia Industrial e Gestão. Faculdade de Engenharia. Universidade do Porto. 201

Statistical Analysis of Seismicity Catalog of Alaska: The mysteries of the timeseries

Abstract:This dissertation presents the results of applying three independent statistical techniques on the seismic catalog of Alaska and Aleutian subduction zone. I perform Visibility Graph Analysis and Multifractal Detrended Fluctuation Analysis respectively on the seismic catalogs of several defined seismogenic zones in surface and depth. Forecasting earthquake hazard is based on the assumption that the Gutenberg-Richter relation represents the size distribution of future earthquakes and we show that the series produced by these methods have properties with close correlation with the b-value of the Gutenberg-Richter law. Visibility graph analysis basically maps a time series into the networks of nodes and connection and we want to show that produced network keeps a relationship with seismic characteristics of the region. Same goes for the multifractal detrended fluctuation analysis which studies the multifractality of the seismic catalogs as magnitude time series. I am also trying to improve the spatial information of the catalog using the Condensation method based on the location error. It will produce a new catalog that differs with the original one by the new assigned weight to the events according to their accuracy relative to the neighboring events. Using this statistical method will contribute to the discovery of previously unknown active structures and a better understanding of seismic hazards in Alaska

Common Agricultural Policy implementation and value chain governance in Germany

Die Agrarpolitik in den Ländern der OECD hat sich seit Mitte der 1980er Jahre stark verändert. Lange Zeit galt die Landwirtschaft als exzeptioneller Wirtschaftszweig, der umfangreiche staatliche Unterstützung für Erzeuger:innen benötigt, um Ernährungssicherheit zu gewährleisten. Heute befasst sich Agrarpolitik auch mit politikfeldübergreifenden Themen wie Verbraucherschutz, Tierwohl und ökologischer Nachhaltigkeit. Dieser Wandel ging mit neuen Politikzielen und -instrumenten, offeneren Institutionen und komplexeren Akteurskonstellationen einher. Gleichzeitig ist Agrarpolitik weiterhin auf Erzeuger:innen ausgerichtet, wodurch der ‚exzeptionalische‘ Kern – die Stützung landwirtschaftlicher Einkommen – bestehen bleibt. Das Konzept des Post-Exzeptionalismus beschreibt dieses Nebeneinander von alten und neuen Ideen, Institutionen, Akteuren, Politikzielen und -instrumenten, wodurch Spannungen in den Politikarrangements entstehen können. Diese Dissertation hat das Ziel am Beispiel der Gemeinsamen Agrarpolitik (GAP) der Europäischen Union (EU) und von Governance-Aktivitäten in landwirtschaftlichen Wertschöpfungsketten in Deutschland zu einem besseren Verständnis dieser Spannungen beizutragen. Auf Grundlage einer Kombination verschiedener Ansätze der Public Policy- und Governance-Analyse untersucht diese Dissertation, wie sich die Spannungen in (i) der Ausgestaltung der Instrumente im GAP-Policy-Mix (2014-2022), (ii) den Diskurskoalitionen und Frames nationaler Stakeholdern in der Debatte zur GAP nach 2022, (iii) dem Verhältnis zwischen Staat und Landwirt:innen und (iv) den Koordinierungsaktivitäten in Wertschöpfungsketten in Deutschland zeigen. Die Ergebnisse zeigen, dass die Details der GAP-Umsetzung und Governance-Aktivitäten entscheidend für die (Nicht-)Angleichung der alten und neuen Elemente in der Agrarpolitik sind. Ihre Ausgestaltung handelt sich also nicht um rein technische, administrative oder unternehmerische, sondern vielmehr um zutiefst politische Aktivitäten.Agricultural policy in OECD countries has changed considerably since the mid-1980s. Long treated as an exceptional economic sector in need of extensive state support to ensure food security, agricultural policy now also aims to address more cross-cutting issues, including consumer protection, animal welfare and environmental sustainability. Novel objectives and policy instruments, a more open institutional framework and increasingly complex actor constellations have accompanied this shift. At the same time, agricultural policy has predominantly remained producer-oriented, perpetuating the exceptionalist core of farm income support. The term post-exceptionalism aims to capture the tensions arising from the juxtaposition of old and new ideas, institutions, actors, and objectives and policy instruments in agricultural policy. This dissertation aims to provide a better understanding of the tensions inherent in post-exceptionalist arrangements in agricultural policy, with the implementation of the European Union’s (EU) Common Agricultural Policy (CAP) and governance activities in agri-food value chains in Germany as an example. Combining different approaches of public policy and governance analysis, the thesis examines how the tensions play out in (i) the design of instrument calibrations in the CAP policy mix (2014-2022), (ii) discourse coalitions and frames among national stakeholders in the run-up to the CAP post-2022, (iii) the relationship between the state and farmers underlying direct payment implementation for the CAP 2023-2027, (iv) and coordination activities in the governance of sustainability-based agri-food value chains in Germany. The results of this dissertation show that the very details of CAP implementation and governance activities in value chains are decisive for the (non)alignment of old and new elements of agricultural policy. Thus, they constitute not a mere technical, administrative or entrepreneurial but rather a political activity