Phase Transitions of the Typical Algorithmic Complexity of the Random Satisfiability Problem Studied with Linear Programming

Here we study the NP-complete $K$-SAT problem. Although the worst-case complexity of NP-complete problems is conjectured to be exponential, there exist parametrized random ensembles of problems where solutions can typically be found in polynomial time for suitable ranges of the parameter. In fact, random $K$-SAT, with $\alpha=M/N$ as control parameter, can be solved quickly for small enough values of $\alpha$. It shows a phase transition between a satisfiable phase and an unsatisfiable phase. For branch and bound algorithms, which operate in the space of feasible Boolean configurations, the empirically hardest problems are located only close to this phase transition. Here we study $K$-SAT ($K=3,4$) and the related optimization problem MAX-SAT by a linear programming approach, which is widely used for practical problems and allows for polynomial run time. In contrast to branch and bound it operates outside the space of feasible configurations. On the other hand, finding a solution within polynomial time is not guaranteed. We investigated several variants like including artificial objective functions, so called cutting-plane approaches, and a mapping to the NP-complete vertex-cover problem. We observed several easy-hard transitions, from where the problems are typically solvable (in polynomial time) using the given algorithms, respectively, to where they are not solvable in polynomial time. For the related vertex-cover problem on random graphs these easy-hard transitions can be identified with structural properties of the graphs, like percolation transitions. For the present random $K$-SAT problem we have investigated numerous structural properties also exhibiting clear transitions, but they appear not be correlated to the here observed easy-hard transitions. This renders the behaviour of random $K$-SAT more complex than, e.g., the vertex-cover problem.Comment: 11 pages, 5 figure

PQL: A Declarative Query Language over Dynamic Biological Schemata

We introduce the PQL query language (PQL) used in the GeneSeek genetic data integration project. PQL incorporates many features of query languages for semi-structured data. To this we add the ability to express metadata constraints like intended semantics and database curation approach. These constraints guide the dynamic generation of potential query plans. This allows a single query to remain relevant even in the presence of source and mediated schemas that are continually evolving, as is often the case in data integration

Tabling as a Library with Delimited Control

Tabling is probably the most widely studied extension of Prolog. But despite its importance and practicality, tabling is not implemented by most Prolog systems. Existing approaches require substantial changes to the Prolog engine, which is an investment out of reach of most systems. To enable more widespread adoption, we present a new implementation of tabling in under 600 lines of Prolog code. Our lightweight approach relies on delimited control and provides reasonable performance.Comment: 15 pages. To appear in Theory and Practice of Logic Programming (TPLP), Proceedings of ICLP 201

Larry Wos - Visions of automated reasoning

This paper celebrates the scientific discoveries and the service to the automated reasoning community of Lawrence (Larry) T. Wos, who passed away in August 2020. The narrative covers Larry's most long-lasting ideas about inference rules and search strategies for theorem proving, his work on applications of theorem proving, and a collection of personal memories and anecdotes that let readers appreciate Larry's personality and enthusiasm for automated reasoning

Proceedings of QG2010: The Third Workshop on Question Generation

These are the peer-reviewed proceedings of "QG2010, The Third Workshop on Question Generation". The workshop included a special track for "QGSTEC2010: The First Question Generation Shared Task and Evaluation Challenge". QG2010 was held as part of The Tenth International Conference on Intelligent Tutoring Systems (ITS2010)

Spartan Daily, February 14, 1989

Volume 92, Issue 13https://scholarworks.sjsu.edu/spartandaily/7803/thumbnail.jp

Is World Trade Organization Information Good Enough? How a Systematic Reflection by Members on Transparency Could Promote Institutional learning. Bertelsmann Stiftung GED Focus Paper

The World Trade Organization (WTO) has three primary tasks: to negotiate new rules, monitor implementation, and settle any disputes that arise. It is not fulfilling any of these tasks very well at the moment. Should Members just muddle along, hoping for the best, or seek external advice on how to change the WTO operating system? I suggest a third possibility: should Members encourage institutional learning? It helps that at least some Members know that they have a problem. In July 2017, a communication to the Gen-eral Council from a group of 47 developing and developed Members said, first, that the political will to find compromises and to forge consensus is lacking (WTO, 2017c). WTO Members have failed for years to agree that the Doha Round is dead so a new negotiation framework cannot be created. The second observation from the group informally known as the Friends of the System is that compliance with notification obligations is often unsatisfactory, thereby undermining the WTO’s monitoring function because information is late, incomplete or of low quality. These two self-criticisms, about political will to find consensus, and insufficient provision of infor-mation, are related: both are a symptom, not a cause; both signify the lack of a shared understanding of what WTO is for. Some of the explanations for the WTO’s difficulties lie outside the organization in a general malaise of multilater-alism (Wolfe, 2015b; Wolfe, 2017b), now exacerbated by an Administration in Washington that in putting America First sees a competitor, not a partner, in China, but continuing as before and hoping for a better outcome would be foolish. Muddling through is no solution, and outsiders cannot help. Could a systematic discussion of transpar-ency help Members to recover a shared sense of collective purpose