Confluent Orthogonal Drawings of Syntax Diagrams

We provide a pipeline for generating syntax diagrams (also called railroad diagrams) from context free grammars. Syntax diagrams are a graphical representation of a context free language, which we formalize abstractly as a set of mutually recursive nondeterministic finite automata and draw by combining elements from the confluent drawing, layered drawing, and smooth orthogonal drawing styles. Within our pipeline we introduce several heuristics that modify the grammar but preserve the language, improving the aesthetics of the final drawing.Comment: GD 201

Solving Irregular Strip Packing Problems With Free Rotations Using Separation Lines

Solving nesting problems or irregular strip packing problems is to position polygons in a fixed width and unlimited length strip, obeying polygon integrity containment constraints and non-overlapping constraints, in order to minimize the used length of the strip. To ensure non-overlapping, we used separation lines. A straight line is a separation line if given two polygons, all vertices of one of the polygons are on one side of the line or on the line, and all vertices of the other polygon are on the other side of the line or on the line. Since we are considering free rotations of the polygons and separation lines, the mathematical model of the studied problem is nonlinear. Therefore, we use the nonlinear programming solver IPOPT (an algorithm of interior points type), which is part of COIN-OR. Computational tests were run using established benchmark instances and the results were compared with the ones obtained with other methodologies in the literature that use free rotation

Simplifying knowledge creation and access for end-users on the SW

In this position paper, we argue that improved mechanisms for knowledge acquisition and access on the semantic web (SW) will be necessary before it will be adopted widely by end-users. In particular, we propose an investigation surrounding improved languages for knowledge exchange, better UI mechanisms for interaction, and potential help from user modeling to enable accurate, efficient, SW knowledge modeling for everyone

Towards Efficient Abstractions for Concurrent Consensus

Consensus is an often occurring problem in concurrent and distributed programming. We present a programming language with simple semantics and build-in support for consensus in the form of communicating transactions. We motivate the need for such a construct with a characteristic example of generalized consensus which can be naturally encoded in our language. We then focus on the challenges in achieving an implementation that can efficiently run such programs. We setup an architecture to evaluate different implementation alternatives and use it to experimentally evaluate runtime heuristics. This is the basis for a research project on realistic programming language support for consensus.Comment: 15 pages, 5 figures, symposium: TFP 201

Moral imagination or heuristic toolbox? Events and the risk assessment of structured financial products in the financial bubble

The paper uses the example of the failure of bankers and financial managers to understand the risks of dealing in structured financial products, prior to the financial collapse, to investigate how people respond to crises. It focuses on whether crises cause people to challenge their habitual frames by the application of moral imagination. It is proposed that the structure of financial products and their markets triggered the use of heuristics that contributed to the underestimation of risks. It is further proposed that such framing heuristics are highly specialised to specific contexts, and are part of a wider set of heuristics that people carry in their cognitive ‘adaptive tool boxes’. Consequently, it is argued, when a crisis occurs the heuristics are not challenged, but are simply put away, and other more appropriate heuristics put to use until a sense of normality returns, and the use of the old heuristics is resumed

Superconductivity without attraction in a quasi-one-dimensional metal

An array of one-dimensional conductors coupled by transverse hopping and interaction is studied with the help of a variational wave function. This wave function is devised as to account for one-dimensional correlation effects. We show that under broad conditions our system possesses the superconducting ground state even if no attraction is present. The superconducting mechanism is of many-body nature and deviates substantially from BCS. The phase diagram of the model is mapped. It consists of two ordered phases competing against each other: density wave, spin or charge, and unconventional superconductivity. These phases are separated by the first order transition. The symmetry of the superconducting order parameter is a non-universal property. It depends on particulars of the Hamiltonian. Within the framework of our model possible choices are the triplet $f$-wave and the singlet $d_{xy}$-wave. Organic quasi-one-dimensional superconductors have similar phase diagram.Comment: 12 pages, 2 Encapsulated PostScript figures, revtex4; the model's Hamiltonian is revised as compared to previous version, this revision affects prediction of the order parameter symmetr