12223354
Disjoint NP-pairs
We study the question of whether the class DisNP of disjoint pairs (A, B) of NP-sets contains a complete pair. The question relates to the question of whether optimal proof systems exist, and we relate it to the previously studied question of whether there exists a disjoint pair of NP-sets that is NP-hard. We show under reasonable hypotheses that nonsymmetric disjoint NP-pairs exist, which provide additional evidence for the existence of P-inseparable disjoint NP-pairs. We construct an oracle relative to which the class of disjoint NP-pairs does not have a complete pair, an oracle relative to which optimal proof systems exist, hence complete pairs exist, but no pair is NP-hard, and an oracle relative to which complete pairs exist, but optimal proof systems do not exist.
15844013
Survey of Disjoint NP-pairs and Relations to Propositional Proof Systems
We survey recent results on disjoint NP-pairs. In particular, we survey the relationship of disjoint NP-pairs to the theory of proof systems for propositional calculus.
11528752
Redundancy in Complete Sets
We show that a set is m-autoreducible if and only if it is m-mitotic. This solves a long standing open question in a surprising way. As a consequence of this unconditional result and recent work by Glaser et al. [12], complete sets for all of the following complexity classes are m-mitotic: NP, coNP, $\bigoplus$P, PSPACE, and NEXP, as well as all levels of PH, MODPH, and the Boolean hierarchy over NP. In the cases of NP, PSPACE, NEXP, and PH, this at once answers several well-studied open questions. These results tell us that complete sets share a redundancy that was not known before. In particular, every NP-complete set A splits into two NP-complete sets A1 and A2.
9292941
Chaff: engineering an efficient SAT solver
Boolean satisfiability is probably the most studied of the combinatorial optimization/search problems. Significant effort has been devoted to trying to provide practical solutions to this problem for problem instances encountered in a range of applications in electronic design automation (EDA), as well as in artificial intelligence (AI). This study has culminated in the development of several SAT packages, both proprietary and in the public domain (e.g. GRASP, SATO) which find significant use in both research and industry. Most existing complete solvers are variants of the Davis-Putnam (DP) search algorithm. In this paper we describe the development of a new complete solver, Chaff which achieves significant performance gains through careful engineering of all aspects of the search-especially a particularly efficient implementation of Boolean constraint propagation (BCP) and a novel low overhead decision strategy. Chaff has been able to obtain one to two orders of magnitude performance improvement on difficult SAT benchmarks in comparison with other solvers (DP or otherwise), including GRASP and SATO.
18028053
An Experimental Study of Increasing Diversity for Case-Based Diagnosis
Increasing diversity for case-based reasoning (CBR) is an issue that has recently drawn the attention of researchers in the CBR field. Several diversification techniques have been proposed and discussed in the literature. However, whether and to what extent those techniques can bring about benefits to end-users remains in question. In this paper, we report an experiment in applying a diversification technique to a case-based diagnosis tool in a product maintenance domain. The results of this offer some evidence in support of diversification techniques.
18609835
Extraction and visualization of architectural structure based on cross references among object files
Reverse engineering of legacy systems is a knowledge-intensive process to reconstruct the understanding of a system. A semi-automatic process that can extract architecture level structure from legacy systems is introduced in This work. Exact facts related to cross-references among ELF objects are extracted from files automatically, and then partitioned into hierarchical groups by close cooperation between domain experts and an assistant tool DEREF. By resolving the cross references among these groups, the architectural structure is reconstructed and then visualized using auto-layout techniques. A case study on three embedded operating system demonstrates that this process can be used to obtain a comprehensive understanding about legacy systems even without any a priori knowledge about its design.
2595966
Color demosaicking via directional linear minimum mean square-error estimation
Digital cameras sample scenes using a color filter array of mosaic pattern (e.g., the Bayer pattern). The demosaicking of the color samples is critical to the image quality. This paper presents a new color demosaicking technique of optimal directional filtering of the green-red and green-blue difference signals. Under the assumption that the primary difference signals (PDS) between the green and red/blue channels are low pass, the missing green samples are adaptively estimated in both horizontal and vertical directions by the linear minimum mean square-error estimation (LMMSE) technique. These directional estimates are then optimally fused to further improve the green estimates. Finally, guided by the demosaicked full-resolution green channel, the other two color channels are reconstructed from the LMMSE filtered and fused PDS. The experimental results show that the presented color demosaicking technique outperforms the existing methods both in PSNR measure and visual perception.
44970083
Web Services Relationships Binding for Dynamic e-Business Integration
Web services are becoming a major research topic for computer scientists, engineers and business consulting professionals. In this preface, I would like to outline the challenges of the current Web services research topics from the modeling, in-teroperability, and mathematical foundations points of view. Then I will introduce some research opportunities and possible future directions for moving Web services forward via some illustrative ideas such as business semantic computing as well as killer application driven Web services research approaches. For the business semantic computing aspect I will present some example application domains such as federated Web services discovery, dynamic Web services composition and extended business collaboration.