A Dichotomy Theorem for the Approximate Counting of Complex-Weighted Bounded-Degree Boolean CSPs

We determine the computational complexity of approximately counting the total weight of variable assignments for every complex-weighted Boolean constraint satisfaction problem (or CSP) with any number of additional unary (i.e., arity 1) constraints, particularly, when degrees of input instances are bounded from above by a fixed constant. All degree-1 counting CSPs are obviously solvable in polynomial time. When the instance's degree is more than two, we present a dichotomy theorem that classifies all counting CSPs admitting free unary constraints into exactly two categories. This classification theorem extends, to complex-weighted problems, an earlier result on the approximation complexity of unweighted counting Boolean CSPs of bounded degree. The framework of the proof of our theorem is based on a theory of signature developed from Valiant's holographic algorithms that can efficiently solve seemingly intractable counting CSPs. Despite the use of arbitrary complex weight, our proof of the classification theorem is rather elementary and intuitive due to an extensive use of a novel notion of limited T-constructibility. For the remaining degree-2 problems, in contrast, they are as hard to approximate as Holant problems, which are a generalization of counting CSPs.Comment: A4, 10pt, 20 pages. This revised version improves its preliminary version published under a slightly different title in the Proceedings of the 4th International Conference on Combinatorial Optimization and Applications (COCOA 2010), Lecture Notes in Computer Science, Springer, Vol.6508 (Part I), pp.285--299, Kailua-Kona, Hawaii, USA, December 18--20, 201

BCFA: Bespoke Control Flow Analysis for CFA at Scale

Many data-driven software engineering tasks such as discovering programming patterns, mining API specifications, etc., perform source code analysis over control flow graphs (CFGs) at scale. Analyzing millions of CFGs can be expensive and performance of the analysis heavily depends on the underlying CFG traversal strategy. State-of-the-art analysis frameworks use a fixed traversal strategy. We argue that a single traversal strategy does not fit all kinds of analyses and CFGs and propose bespoke control flow analysis (BCFA). Given a control flow analysis (CFA) and a large number of CFGs, BCFA selects the most efficient traversal strategy for each CFG. BCFA extracts a set of properties of the CFA by analyzing the code of the CFA and combines it with properties of the CFG, such as branching factor and cyclicity, for selecting the optimal traversal strategy. We have implemented BCFA in Boa, and evaluated BCFA using a set of representative static analyses that mainly involve traversing CFGs and two large datasets containing 287 thousand and 162 million CFGs. Our results show that BCFA can speedup the large scale analyses by 1%-28%. Further, BCFA has low overheads; less than 0.2%, and low misprediction rate; less than 0.01%.Comment: 12 page

Morphometric Analysis Applied to Wood Structure. I. Cross-Sectional Cell Shape and Area Change in Red Spruce

A new method for assessing seasonal change in cross-sectional tracheid shape in conifers is described and tested with red spruce. An equation (called circularity index) was used to reference cell shape to a circle with equal circumference. Cell lumen boundaries were measured on a rear projection digitizer coupled to a computer. Circularity indices and cell lumen areas were determined, and curves of these parameters were plotted across growth rings. Circularity index curves proved to be a sensitive measure of true latewood, and cell lumen area curves detected variation in transition latewood. Cell-wall area changes that were related to site differences correlated with earlier specific gravity determinations. Cell lumen area curves provided an explanation for nonsignificant specific gravity differences in spruce wood following nitrogen fertilization

Understanding the social in a digital age

Datafication, algorithms, social media and their various assemblages enable massive connective processes, enriching personal interaction and amplifying the scope and scale of public networks. At the same time, surveillance capitalists and the social quantification sector are committed to monetizing every aspect of human communication, all of which threaten ideal social qualities, such as togetherness and connection. This Special Issue brings together a range of voices and provocations around ‘the social’, all of which aim to critically interrogate mediated human connection and their contingent socialities. Conventional methods may no longer be adequate, and we must rethink not only the fabric of the social but the very tools we use to make sense of our changing social formations. This Special Issue raises shared concerns with what the social means today, unpicking and rethinking the seams between digitization and social life that characterize today’s digital age

The Contribution of the Cosmological Constant to the Relativistic Bending of Light Revisited

We study the effect of the cosmological constant $\Lambda$ on the bending of light by a concentrated spherically symmetric mass. Contrarily to previous claims, we show that when the Schwarzschild-de Sitter geometry is taken into account, $\Lambda$ does indeed contribute to the bending.Comment: 5 pages, 2 figure

A Laboratory Evaluation of Leachate from the Jim Bridger Power Plant Scrubber Wastes

Introduction: Scrubber wastes obtained in an affort to limit air pollution generated by coal-fired pwoer plants may contribute to another possible sources of pollution. To date, scrubber wastse have been in a liquid phase which causes disposal problems partially due to the liquid characteristics. The use of solid scrubber wastes and the land deposition of such wastes is proposed. The feasibility of solid scrubber wastes disposal in landfills is under question. The primary area of concern is the effect that water percolation through such wastes would have on groundwater quality parameters. Contamination could result either as precipitation travels downward through the wastes and into the water table or as the water table rises into the scrubber wastes and then retreats. Groundwater contamination is a key concern because it is largely irreversible and has long term consequences. Objective: Disposal methods for coal-fired power plant fly ask and scrubber wastes present a potential for the contamination of groundwater aquifers. In this study the general objective was to evaluate the physical and chemical characteristics of the leachates of scrubber weastes and associated disposal materials separately and in appropriate combinations using laboratory bench scale techniques. Two appraoches, namely column leaching and batch elutriation, were developed and used to provide indicators characterisitic of the materials tested