Reinforcement learning based local search for grouping problems: A case study on graph coloring

Grouping problems aim to partition a set of items into multiple mutually disjoint subsets according to some specific criterion and constraints. Grouping problems cover a large class of important combinatorial optimization problems that are generally computationally difficult. In this paper, we propose a general solution approach for grouping problems, i.e., reinforcement learning based local search (RLS), which combines reinforcement learning techniques with descent-based local search. The viability of the proposed approach is verified on a well-known representative grouping problem (graph coloring) where a very simple descent-based coloring algorithm is applied. Experimental studies on popular DIMACS and COLOR02 benchmark graphs indicate that RLS achieves competitive performances compared to a number of well-known coloring algorithms

Automated Heuristic Generation By Intelligent Search

This thesis presents research that examines the effectiveness of several different program synthesis techniques when used to automate the creation of heuristics for a local search-based Boolean Satisfiability solver. Previous research focused on the automated creation of heuristics has almost exclusively relied on evolutionary computation techniques such as genetic programming to achieve its goal. In wider program synthesis research, there are many other techniques which can automate the creation of programs. However, little effort has been expended on utilising these alternate techniques in automated heuristic creation. In this thesis we analyse how three different program synthesis techniques perform when used to automatically create heuristics for our problem domain. These are genetic programming, exhaustive enumeration and a new technique called local search program synthesis. We show how genetic programming can create effective heuristics for our domain. By generating millions of heuristics, we demonstrate how exhaustive enumeration can create small, easily understandable and effective heuristics. Through an analysis of the memoized results from the exhaustive enumeration experiments, we then describe local search program synthesis, a program synthesis technique based on the minimum tree edit distance metric. Using the memoized results, we simulate local search program synthesis on our domain, and present evidence that suggests it is a viable technique for automatically creating heuristics. We then define the necessary algorithms required to use local search program synthesis without any reliance on memoized data. Through experimentation, we show how local search program synthesis can be used to create effective heuristics for our domain. We then identify examples of heuristics created that are of higher quality than those produced from other program synthesis methods. At certain points in this thesis, we perform a more detailed analysis on some of the heuristics created. Through this analysis, we show that, on certain problem instances, several of the heuristics have better performance than some state-of-the-art, hand-crafted heuristics

Automated Heuristic Generation By Intelligent Search

This thesis presents research that examines the effectiveness of several different program synthesis techniques when used to automate the creation of heuristics for a local search-based Boolean Satisfiability solver. Previous research focused on the automated creation of heuristics has almost exclusively relied on evolutionary computation techniques such as genetic programming to achieve its goal. In wider program synthesis research, there are many other techniques which can automate the creation of programs. However, little effort has been expended on utilising these alternate techniques in automated heuristic creation. In this thesis we analyse how three different program synthesis techniques perform when used to automatically create heuristics for our problem domain. These are genetic programming, exhaustive enumeration and a new technique called local search program synthesis. We show how genetic programming can create effective heuristics for our domain. By generating millions of heuristics, we demonstrate how exhaustive enumeration can create small, easily understandable and effective heuristics. Through an analysis of the memoized results from the exhaustive enumeration experiments, we then describe local search program synthesis, a program synthesis technique based on the minimum tree edit distance metric. Using the memoized results, we simulate local search program synthesis on our domain, and present evidence that suggests it is a viable technique for automatically creating heuristics. We then define the necessary algorithms required to use local search program synthesis without any reliance on memoized data. Through experimentation, we show how local search program synthesis can be used to create effective heuristics for our domain. We then identify examples of heuristics created that are of higher quality than those produced from other program synthesis methods. At certain points in this thesis, we perform a more detailed analysis on some of the heuristics created. Through this analysis, we show that, on certain problem instances, several of the heuristics have better performance than some state-of-the-art, hand-crafted heuristics

A Serendipitous Software Framework for Facilitating Collaboration in Computational Intelligence

A major flaw in the academic system, particularly pertaining to computer science, is that it rewards specialisation. The highly competitive quest for new scientific developments, or rather the quest for a better reputation and more funding, forces researchers to specialise in their own fields, leaving them little time to properly explore what others are doing, sometimes even within their own field of interest. Even the peer review process, which should provide the necessary balance, fails to achieve much diversity, since reviews are typically performed by persons who are again specialists in the particular field of the work. Further, software implementations are rarely reviewed, having as a consequence the publishing of untenable results. Unfortunately, these factors contribute to an environment which is not conducive to collaboration, a cornerstone of academia | building on the work of others. This work takes a step back and examines the general landscape of computational intelligence from a broad perspective, drawing on multiple disciplines to formulate a collaborative software platform, which is flexible enough to support the needs of this diverse research community. Interestingly, this project did not set out with these goals in mind, rather it evolved, over time, from something more specialised into the general framework described in this dissertation. Design patterns are studied as a means to manage the complexity of the computational intelligence paradigm in a flexible software implementation. Further, this dissertation demonstrates that releasing research software under an open source license eliminates some of the deficiencies of the academic process, while preserving, and even improving, the ability to build a reputation and pursue funding. Two software packages have been produced as products of this research: i) CILib, an open source library of computational intelligence algorithms; and ii) CiClops, which is a virtual laboratory for performing experiments that scale over multiple workstations. Together, these software packages are intended to improve the quality of research output and facilitate collaboration by sharing a repository of simulation data, statistical analysis tools and a single software implementation.Dissertation (MSc)--University of Pretoria, 2006.Computer ScienceUnrestricte

The Power and the Purse: Aspects of the Genesis and Implementation of the Metropolitan Poor Act 1867

PhdThis thesis examines the genesis and implementation of two provisions of the Metropolitan Poor Act 1867: rate equalisation and the appointment of central government nominees to local poor law bodies. It is contended that while the Act pointed towards the twentieth-century state in that it led to a growth in government and to redistribution of the public spending burden, a new type of gentlemanly safeguard against elected power underpinned these developments. A radical call for redistribution of wealth in the metropolis, coming largely not from the East End but from the west, the south and the City, played a significant part in the genesis of the Act's innovatory restraining step of appointing Poor Law Board nominees to metropolitan bodies. The aim, it is argued, was to dilute the representative base of these bodies as some of their poor law spending came within the compass of the new metropolitan common purse: a step taken in the same year that the representative base for parliament was widened by the passing of the Second Reform Act. The thesis examines the manuscript records of the major metropolitan movement for rate equalisation,analyses decision-making on the Act's largest and longest-running poor law body, the Metropolitan Asylums Board, in its first four years, and presents a census-based socio-economic comparative study of this board's elected and elite nominated managers. The role of central government (ministers and officials) in the state growth that arose out of the Act is also considered. The conclusion reached is that in the metropolis in the 1860s the conscious, planned and more centralised growth of poor law services, and the accompanying partial redistribution of wealth from richer to poorer areas, both arising largely as a result of insistent reformist and radical pressure, took place within a context of gentlemanly ingenuity in finding new ways of retaining influence and power

Celebrating Economies of Change: Brave Visions for Inclusive Futures

This issue has been inspired by a path-breaking conference held by the Canadian Society for Ecologi-cal Economics (CANSEE), which took place this past May 2019 in Waterloo, Ontario. Entitled Engaging Economies of Change, the conference aimed to ex-pand existing research networks in the economy-environment nexus by building connections beyond the academy in order to meaningfully engage with the practicalities of building and implementing change. This issue captures the rich content shared during the event, as well as descriptions of the pro-cesses and efforts made to create a welcoming and respectful space where academics and community activists could build alliances and discuss common challenges. The conference organizers – all graduate students and activists themselves -- called this ‘building a brave space’.This research was supported by the Social Sciences and Humanities Research Council of Canad

Proceedings of the 21st Conference on Formal Methods in Computer-Aided Design – FMCAD 2021

The Conference on Formal Methods in Computer-Aided Design (FMCAD) is an annual conference on the theory and applications of formal methods in hardware and system verification. FMCAD provides a leading forum to researchers in academia and industry for presenting and discussing groundbreaking methods, technologies, theoretical results, and tools for reasoning formally about computing systems. FMCAD covers formal aspects of computer-aided system design including verification, specification, synthesis, and testing

Migrant Worker Lifeworlds of Beirut

A country of approximately 4 million citizens, Lebanon is home to over half a million Asian and black African migrant workers concentrated in its capital city of Beirut. An estimated one quarter of Lebanese households employ a live-in female migrant domestic worker on a full time basis. Over the last decade, many of these women have fled domestic confinement to enter Lebanon’s informal labour market, and have recently been joined by hundreds of thousands of Syrian refugees fleeing war across the country’s eastern border. This dissertation examines the social worlds of these migrant workers. It demonstrates that non-Arab migrant workers in Beirut are not simply temporary workers, but constitute a specific subject category structured by socioeconomic relations that determine the possibility of their life in the city. Specifically, it argues that migrant workers in Beirut are subjects denied recognition, and who therefore lie outside the nation-state, while having forged an urban belonging inside the city. I demonstrate this by examining migrant workers’ interactions with the joint nexus of citizen-state authority, their experiences of time in both labour and rest, their modes of receiving address and inhabiting speech in the Arabic language, and their intimate and collective relations in the city. Together with growing numbers of male Syrian refugees, migrant workers in Beirut have created an urban underground that has transformed both what and who it means to live in the city today. This dissertation offers an ethnographic map of these transformations

The Neoliberal Age?

The late twentieth and early twenty-first centuries are commonly characterised as an age of ‘neoliberalism’ in which individualism, competition, free markets, and privatisation came to dominate Britain’s politics, economy and society. This historical framing has proven to be highly controversial, within both academia and contemporary political/public debate. Standard accounts of neoliberalism generally focus on the influence of political ideas in reshaping British politics. According to this narrative, neoliberalism was a right-wing ideology, peddled by political economists, think-tanks, and politicians from the 1930s onwards, which finally triumphed in the 1970s and 1980s. The Neoliberal Age? suggests this narrative is too simplistic. Where the standard story sees neoliberalism as right-wing, this book points to some left-wing origins, too. Where the standard story emphasises the agency of think-tanks and politicians, this book shows that other actors from the corporate world were also highly significant. Where the standard story can suggest that neoliberalism transformed subjectivities and social lives, this book shows other forces which helped make Britain more individualistic in the late twentieth century. The analysis thus takes neoliberalism seriously but also shows that it cannot be the only explanatory framework for understanding contemporary Britain, and that ‘neoliberal’ cannot be the only descriptor used to categorise Britain in the past 50 years. The book showcases cutting-edge research, making it useful to researchers and students, as well as to those interested in understanding the forces that have shaped our recent past