15,292 research outputs found

    A heuristic approach for big bucket multi-level production planning problems

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    Multi-level production planning problems in which multiple items compete for the same resources frequently occur in practice, yet remain daunting in their difficulty to solve. In this paper, we propose a heuristic framework that can generate high quality feasible solutions quickly for various kinds of lot-sizing problems. In addition, unlike many other heuristics, it generates high quality lower bounds using strong formulations, and its simple scheme allows it to be easily implemented in the Xpress-Mosel modeling language. Extensive computational results from widely used test sets that include a variety of problems demonstrate the efficiency of the heuristic, particularly for challenging problems

    Governance: public governance to social innovation?

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    ArticleThis paper reviews governance and public governance related to an emerging area of policy interest – social innovation. The European Commission’s White Paper on European Governance (2001) focused on openness, participation, accountability, effectiveness and coherence in public policy as characteristics of good governance. The EC has prioritised social innovation to address policy problems. Yet, the extant literature and research on social innovation is sparse. The paper questions whether it is a new mode of governance which contributes to good governance or a continuum of neoliberal reforms of the state which alters the relationship between the state, market and civil society

    Nominal Abstraction

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    Recursive relational specifications are commonly used to describe the computational structure of formal systems. Recent research in proof theory has identified two features that facilitate direct, logic-based reasoning about such descriptions: the interpretation of atomic judgments through recursive definitions and an encoding of binding constructs via generic judgments. However, logics encompassing these two features do not currently allow for the definition of relations that embody dynamic aspects related to binding, a capability needed in many reasoning tasks. We propose a new relation between terms called nominal abstraction as a means for overcoming this deficiency. We incorporate nominal abstraction into a rich logic also including definitions, generic quantification, induction, and co-induction that we then prove to be consistent. We present examples to show that this logic can provide elegant treatments of binding contexts that appear in many proofs, such as those establishing properties of typing calculi and of arbitrarily cascading substitutions that play a role in reducibility arguments.Comment: To appear in the Journal of Information and Computatio

    Prudent banks and creative mimics : can we tell the difference?

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    The recent financial crisis has forced a rethink of banking regulation and supervision and the role of financial innovation. We develop a model where prudent banks may signal their type through high capital ratios. Capital regulation may ensure separation in equilibrium but deposit insurance will tend to increase the level of capital required. If supervision detects risky behaviour ex ante then it is complementary to capital regulation. However, financial innovation may erode supervisors' ability to detect risk and capital levels should then be higher. But regulators may not be aware their capacities have been undermined. We argue for a four-prong policy response with higher bank capital ratios, enhanced supervision, limits to the use of complex financial instruments and Coco's. Our results may support the institutional arrangements proposed recently in the UK
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