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Elektronische Version der gedr. Ausg. 199

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Elektronische Version der gedr. Ausg. 199

Recognition and Exploitation of Gate Structure in SAT Solving

In der theoretischen Informatik ist das SAT-Problem der archetypische Vertreter der Klasse der NP-vollständigen Probleme, weshalb effizientes SAT-Solving im Allgemeinen als unmöglich angesehen wird. Dennoch erzielt man in der Praxis oft erstaunliche Resultate, wo einige Anwendungen Probleme mit Millionen von Variablen erzeugen, die von neueren SAT-Solvern in angemessener Zeit gelöst werden können. Der Erfolg von SAT-Solving in der Praxis ist auf aktuelle Implementierungen des Conflict Driven Clause-Learning (CDCL) Algorithmus zurückzuführen, dessen Leistungsfähigkeit weitgehend von den verwendeten Heuristiken abhängt, welche implizit die Struktur der in der industriellen Praxis erzeugten Instanzen ausnutzen. In dieser Arbeit stellen wir einen neuen generischen Algorithmus zur effizienten Erkennung der Gate-Struktur in CNF-Encodings von SAT Instanzen vor, und außerdem drei Ansätze, in denen wir diese Struktur explizit ausnutzen. Unsere Beiträge umfassen auch die Implementierung dieser Ansätze in unserem SAT-Solver Candy und die Entwicklung eines Werkzeugs für die verteilte Verwaltung von Benchmark-Instanzen und deren Attribute, der Global Benchmark Database (GBD)

The Role of Cadherins and Ryk on Metastasis and Invasion in Triple Negative Breast Cancer Cell Model: Hs578T/Hs578Ts(i)8

Breast cancer is a major cause of death among women in European and North American countries, even with improved methods for diagnosis and therapy. The mortality of breast cancer is mainly due to the migration of the primary tumor to distinct sites in the body and is very common in triple negative breast cancer (TNBC). This type of breast cancer affects younger woman and has a high recurrence rate. Unfortunately, TNBC is extremely difficult to control because of the absence of specific targets for treatment. Therefore, our research aim is to discover new therapeutic targets and identify novel approaches for treatment of TNBC. In this study the isogenic Hs578T/Hs578Ts(i)8 cell model is used. This model consists of two cell lines: the Hs578T cells represent a primary tumor whereas the Hs578Ts(i)8 cells have undergone biochemical changes that makes it more migratory and invasive. This cell model allows studying breast cancer progression since it resembles breast cancer patients that show metastatic disease. The focus of this project is on cell-cell adhesion molecules (cadherins), and the novel receptor tyrosine kinase, Ryk, their interactions and spatiotemporal rearrangements. These molecules are studied using various techniques and methods such as behavioral assays, western blots, coimmunoprecipitation, and immunofluorescence microscopy. The results of our experiments have allowed for determining a role for N-cadherin and cadherin-11, their location, and potential connection with Ryk in invasive TNBC. In summary, this study provides novel valuable insights on the role of cadherins and Ryk in the progression of TNBC

Labor migration, market competition and ethnocentrism: guest workers in Israel and Germany ; Ergebnisse eines Forschungsprojektes und Beschreibung des Datensatzes (ZA-Studien-Nr. 3974)

'The major objective of the research was to examine attitudes and values toward guest workers in Israel and Germany in a comparative perspective. The main objects of examinations are the social conditions which shape the normative system of beliefs, attitudes, stereotypes, prejudice and behaviour toward foreign workers and ethnic minorities. The research was cast within theoretical frameworks that focus on the emergence of prejudice, discrimination and ethnic antagonism in modern societies. Two alternative, but by no means contradictory, models were used. The first is social psychological and centres on such concepts as social distance, prejudice, authoritarianism, and ethnocentrism. The second approach focuses on group competition over resources and rewards in national markets. Data to test the hypotheses were taken from national representative samples of adult citizens in Israel and Germany, respectively. The data was analysed using a variety of multivariate statistical models. It was our aim to contribute to a better understanding of the Israeli and German societies and to the theoretical knowledge regarding the social conditions that affect the system of values, attitudes, and behaviour toward migrant workers and ethnic minorities in modern societies. The comparison between Germany and Israel was one special point of interest, because Germany has been employing guest workers for more than a quarter of a century whereas Israel only recently began to rely on foreign workers. The influence of guest worker communities on contemporary societies is one significant social and economic problem of modern states. The study tried to increase the understanding of these mechanisms and phenomena.' (author's abstract)

Unit propagation with stable watches

Unit propagation is the hottest path in CDCL SAT solvers, therefore the related data-structures, algorithms and implementation details are well studied and highly optimized. State-of-the-art implementations are based on reduced occurrence tracking with two watched literals per clause and one blocking literal per watcher in order to further reduce the number of clause accesses. In this paper, we show that using runtime statistics for watched literal selection can improve the performance of state-of-the-art SAT solvers. We present a method for efficiently keeping track of spans during which literals are satisfied and using this statistic to improve watcher selection. An implementation of our method in the SAT solver CaDiCaL can solve more instances of the SAT Competition 2019 and 2020 benchmark sets and is specifically strong on satisfiable cryptographic instances

Prevent: what is pre-criminal space?

Prevent is a UK-wide programme within the government’s anti-terrorism strategy aimed at stopping individuals from supporting or taking part in terrorist activities. NHS England’s Prevent Training and Competencies Framework requires health professionals to understand the concept of pre-criminal space. This article examines pre-criminal space, a new term which refers to a period of time during which a person is referred to a specific Prevent-related safeguarding panel, Channel. It is unclear what the concept of pre-criminal space adds to the Prevent programme. The term should be either clarified or removed from the Framework