An Enhanced Features Extractor for a Portfolio of Constraint Solvers

Recent research has shown that a single arbitrarily efficient solver can be significantly outperformed by a portfolio of possibly slower on-average solvers. The solver selection is usually done by means of (un)supervised learning techniques which exploit features extracted from the problem specification. In this paper we present an useful and flexible framework that is able to extract an extensive set of features from a Constraint (Satisfaction/Optimization) Problem defined in possibly different modeling languages: MiniZinc, FlatZinc or XCSP. We also report some empirical results showing that the performances that can be obtained using these features are effective and competitive with state of the art CSP portfolio techniques

Sustaining tenancies in Australia's indigenous town-camps

Indigenous housing is an enduring policy problem in Australia. Policy failure (both rhetoric and reality) has characterised the history of the design, provision and management of housing welfare for Australia’s Indigenous communities in remote and town-camp locations. While the reasons for this are complex and contested, the consequences are more clear-cut: Indigenous people face much higher levels of disadvantage than non-Indigenous Australians. The 2008 reforms mark a significant structural break in government approaches to the Indigenous housing crisis in remote and town-camps communities. Pre-2008, government endorsed a community-housing approach to Indigenous housing provision, advocating for housing policies and programs developed and administered in partnership with Indigenous communities. This policy approach was abandoned with the 2008 government endorsement of a public housing system for the provision and management of Indigenous housing in remote and town-camp communities. Informed by neoliberal views of Indigenous dysfunction, and the individual’s role in this, the government pursues a behavioural change approach to induce tenants to adopt ways of life consistent with western ways of living in a house and managing a tenancy. One important government objective in these reforms is securing sustainable tenancies for Indigenous tenants. Sustainable tenancies not only prevent tenancy failure, but help achieve positive tenancy outcomes (such as stability, security and improved health and well-being). Meeting this objective may provide an important reprieve for Indigenous people from the enduring cycle of policy failure. This thesis aims to analyse how the initial implementation of the 2008 Indigenous housing reforms can lead to sustainable tenancies for residents in town-camp communities. Qualitative research methods were employed to study changes to tenants’ ways of living in Indigenous town-camp communities in the Northern Territory and Western Australia as a result of these reforms. Interviews were conducted with Indigenous tenants and a cross-section of Indigenous housing stakeholders involved in the design and implementation of these reforms in both jurisdictions. The investigation was guided by a dual approach to the analysis of the systems of housing welfare provision and of Indigenous tenants’ lived experience of these systems in order to understand the macro- and micro-level contexts for these housing reforms, how tenants’ ways of living were evolving as a result these reforms, and where opportunities might exist to further optimise positive tenancy outcomes. The primary contribution of this thesis is to bring together a review of the current systems of housing welfare provision in town-camp communities, with a practice-based analysis of the lived experience of housing welfare in Indigenous town-camps. This thesis develop new understandings of how the sustaining tenancies agenda is met within current Indigenous housing welfare reforms, and especially how the criterion for supportive housing management might be achieved through new dynamics in public housing governance. This thesis identifies a series of issues affecting the implementation of the current Indigenous housing reforms and their capacity to attain sustainable tenancies for Indigenous tenants. It concludes by identifying a potential platform (within the constraints of these housing reforms) to optimise positive tenancy outcomes in Indigenous town-camp communities

Speaking vocabulary of first grade children

Thesis (Ed.M.)--Boston Universit

SSA-Based Register Allocation with PBQP

Abstract. Recent research shows that maintaining SSA form allows to split register allocation into separate phases: spilling, register assign-ment and copy coalescing. After spilling, register assignment can be done in polynomial time, but copy coalescing is NP-complete. In this pa-per we present an assignment approach with integrated copy coalescing, which maps the problem to the Partitioned Boolean Quadratic Problem (PBQP). Compared to the state-of-the-art recoloring approach, this re-duces the relative number of swap and copy instructions for the SPEC CINT2000 benchmark to 99.6 % and 95.2%, respectively, while taking 19 % less time for assignment and coalescing

A high-performance matrix-matrix multiplication methodology for CPU and GPU architectures

Current compilers cannot generate code that can compete with hand-tuned code in efficiency, even for a simple kernel like matrix–matrix multiplication (MMM). A key step in program optimization is the estimation of optimal values for parameters such as tile sizes and number of levels of tiling. The scheduling parameter values selection is a very difficult and time-consuming task, since parameter values depend on each other; this is why they are found by using searching methods and empirical techniques. To overcome this problem, the scheduling sub-problems must be optimized together, as one problem and not separately. In this paper, an MMM methodology is presented where the optimum scheduling parameters are found by decreasing the search space theoretically, while the major scheduling sub-problems are addressed together as one problem and not separately according to the hardware architecture parameters and input size; for different hardware architecture parameters and/or input sizes, a different implementation is produced. This is achieved by fully exploiting the software characteristics (e.g., data reuse) and hardware architecture parameters (e.g., data caches sizes and associativities), giving high-quality solutions and a smaller search space. This methodology refers to a wide range of CPU and GPU architectures

NightSplitter: a scheduling tool to optimize (sub)group activities

International audienceHumans are social animals and usually organize activities in groups. However, they are often willing to split temporarily a bigger group in subgroups to enhance their preferences. In this work we present NightSplitter, an on-line tool that is able to plan movie and dinner activities for a group of users, possibly splitting them in subgroups to optimally satisfy their preferences. We first model and prove that this problem is NP-complete. We then use Constraint Programming (CP) or alternatively Simulated Annealing (SA) to solve it. Empirical results show the feasibility of the approach even for big cities where hundreds of users can select among hundreds of movies and thousand of restaurants

Automated Analysis in Feature Modelling and Product Configuration

The automated analysis of feature models is one of the thriving topics of research in the software product line and variability management communities that has attracted more attention in the last years. A recent literature review reported that more than 30 analysis operations have been identi ed and di erent analysis mechanisms have been proposed. Product con guration is a well established research eld with more than 30 years of successful applications in di erent industrial domains. Our hypothesis, that is not really new, is that these two independent areas of research have interesting synergies that have not been fully explored. To try to explore the potential synergies systematically, in this paper we provide a rapid review to bring together these previously disparate streams of work. We de ne a set of research questions and give a preliminary answer to some of them. We conclude that there are many research opportunities in the synergy of these independent areas.Ministerio de Ciencia e Innovación TIN2009- 07366Junta de Andalucía TIC-590