Effective Lower Bounding Techniques for Pseudo-Boolean Optimization

Linear Pseudo-Boolean Optimization (PBO) is a widely used modeling framework in Electronic Design Automation (EDA). Due to significant advances in Boolean Satisfiability (SAT), new algorithms for PBO have emerged, which are effective on highly constrained instances. However, these algorithms fail to handle effectively the information provided by the cost function of PBO. This paper addresses the integration of lower bound estimation methods with SAT-related techniques in PBO solvers. Moreover, the paper shows that the utilization of lower bound estimates can dramatically improve the overall performance of PBO solvers for most existing benchmarks from EDA. 1

Satisfiability-Based Algorithms for Boolean Optimization

This paper proposes new algorithms for the Binate Covering Problem (BCP), a well-known restriction of Boolean Optimization. Binate Covering finds application in many areas of Computer Science and Engineering. In Artificial Intelligence, BCP can be used for computing minimum-size prime implicants of Boolean functions, of interest in Automated Reasoning and Non-Monotonic Reasoning. Moreover, Binate Covering is an essential modeling tool in Electronic Design Automation. The objectives of the paper are to briefly review branch-and-bound algorithms for BCP, to describe how to apply backtrack search pruning techniques from the Boolean Satisfiability (SAT) domain to BCP, and to illustrate how to strengthen those pruning techniques by exploiting the actual formulation of BCP. Experimental results, obtained on representative instances indicate that the proposed techniques provide significant performance gains for a large number of problem instances

On the instability of Reissner-Nordstrom black holes in de Sitter backgrounds

Recent numerical investigations have uncovered a surprising result: Reissner-Nordstrom-de Sitter black holes are unstable for spacetime dimensions larger than 6. Here we prove the existence of such instability analytically, and we compute the timescale in the near-extremal limit. We find very good agreement with the previous numerical results. Our results may me helpful in shedding some light on the nature of the instability.Comment: Published in Phys.Rev.

Revisiting the strengths and limitations of regulatory contracts in infrastructure industries

This paper evaluates regulation by contract in public-private partnerships (PPPs) in infrastructure services. Although the benefits of competition for the market and of regulatory contracts are widely acknowledged, the literature indentifies several failures in their design. These ‘flaws’ are present in both developed and developing countries and arise in all types of contracts. This study analyses both short and long term contracts, focusing on purely contractual PPPs and institutionalized PPPs (mixed companies). The evidence suggests that for all kinds of contracts, the major problems tend to arise in the preparation of public tender documents: the ‘best’ bidder is not often the winner. The likely results include redistribution in favor of the private partner, weak incentives for high performance, and renegotiation of contracts. Moreover, risks are not allocated correctly nor is effective monitoring ensured. This review of contract procedures and design allows us to draw several implications for policy-makers and to present suggestions and recommendations for improving regulatory contracts.regulation by contract; bidding documents; contract design; risk; monitoring