1037525
Graph Drawing by High-Dimensional Embedding
We present a novel approach to the aesthetic drawing of undirected graphs. The method has two phases: first embed the graph in a very high dimension and then project it into the 2-D plane using principal components analysis. Running time is linear in the graph size, and experiments we have carried out show the ability of the method to draw graphs of 105 nodes in few seconds. The new method appears to have several advantages over classical methods, including a significantly better running time, a useful inherent capability to exhibit the graph in various dimensions, and an effective means for interactive exploration of large graphs.
346060
A Multi-scale Algorithm for the Linear Arrangement Problem
Finding a linear ordering of the vertices of a graph is a common problem arising in diverse applications. In this paper we present a linear-time algorithm for this problem, based on the multi-scale paradigm. Experimental results are similar to those of the best known approaches, while the running time is significantly better, enabling it to deal with much larger graphs. The paper contains a general multi-scale construction, which may be used for a broader range of ordering problems.
1830823
Playing with time: on the specification and execution of time-enriched LSCs
We extend live sequence charts (LSCs), a highly expressive variant of sequence diagrams, with timing constructs, thus making the language suitable for specifying the behavioral requirements of time-intensive systems. We follow R. Alur and T.A. Henzinger (see Software Tools for Technology Transfer, vol.1, p.86-109, 1997) in basing the extension on a single clock object. We have implemented the extension in full in our play-engine tool, which provides user-friendly ways to play in the timing constraints, together with a powerful mechanism that can execute, or play out, the time-enriched requirements directly, without the need for an intra-object system model. It seems that in addition to many advantages in testing and requirements engineering, for some kinds of systems this could lead to the requirements actually serving as the final implementation.
8235954
Clustering spatial data using random walks
Discovering significant patterns that exist implicitly in huge spatial databases is an important computational task. A common approach to this problem is to use cluster analysis. We propose a novel approach to clustering, based on the deterministic analysis of random walks on a weighted graph generated from the data. Our approach can decompose the data into arbitrarily shaped clusters of different sizes and densities, overcoming noise and outliers that may blur the natural decomposition of the data. The method requires only O(n log n) time, and one of its variants needs only constant space.
7099239
Statecharts in the making: a personal account
How avionics work led to a graphical language for reactive systems where the diagrams themselves define the system's behavior.