Explaining Propagators for String Edit Distance Constraints

The computation of string similarity measures has been thoroughly studied in the scientific literature and has applications in a wide variety of different areas. One of the most widely used measures is the so called string edit distance which captures the number of required edit operations to transform a string into another given string. Although polynomial time algorithms are known for calculating the edit distance between two strings, there also exist NP-hard problems from practical applications like scheduling or computational biology that constrain the minimum edit distance between arrays of decision variables. In this work, we propose a novel global constraint to formulate restrictions on the minimum edit distance for such problems. Furthermore, we describe a propagation algorithm and investigate an explanation strategy for an edit distance constraint propagator that can be incorporated into state of the art lazy clause generation solvers. Experimental results show that the proposed propagator is able to significantly improve the performance of existing exact methods regarding solution quality and computation speed for benchmark problems from the literature.

A Computer Vision Framework for Automated Shape Retrieval

With the increasing number of images generated every day, textual annotation of images for image mining becomes impractical and inefficient. Thus, computer vision based image retrieval has received considerable interest in recent years. One of the fundamental characteristics of any image representation of an object is its shape which plays a vital role to recognize the object at primitive level. Keeping this view as the primary motivational focus, we propose a shape descriptive frame work using a multilevel tree structured representation called Hierarchical Convex Polygonal Decomposition (HCPD). Such a frame work explores different degrees of convexity of an object’s contour-segments in the course of its construction. The convex and non-convex segments of an object’s contour are discovered at every level of the HCPD-tree generation by repetitive convex-polygonal approximation of contour segments. We have also presented a novel shape-string-encoding scheme for representing the HCPD-tree which allows us touse the popular concept of string-edit distance to compute shape similarity score between two objects. The proposed framework when deployed for similar shape retrieval task demonstrates reasonably good performance in comparison with other popular shape-retrieval algorithms.

Scalable Hardware Mechanism for Partitioned Circuits Operation

For designing hardware with a high-level synthesis tool using a programming language such as C or Java, its large size of logic circuit makes it difficult to implement the design in a single FPGA. In such a case, partitioning the logic circuit and implementing in multiple FPGAs is a commonly used approach. We propose the Scalable Hardware Mechanism, which enables the operation of a partitioned circuit to prevent the degradation of clock frequency by minimizing its dependence on the usage and the type of FPGA. Our mechanism provides a reduced delay by the collective signal transmission with the partitioned AES code generation circuit and the character string edit distance calculation circuit as partitioned circuits. The collective signal transmission has attained 1.27 times improvement in the speed for the AES code generation circuit and 3.16 times improvement for the character string edit distance calculation circuit compared with the circuit by the conventional method.

Phonetic distance and dialect clustering on the Qinghai-Tibet plateau

The goal of this paper is to use string edit distance to describe the synchronic relationship between the Tibetan speech varieties located on the Northeastern edge of the Tibetan Plateau. String edit distance provides a statistical way to compare a large number of linguistic features, in essence producing a statistical bundle of isoglosses. In this way, it can be used as a tool in dialect mapping and synchronic clustering. In this paper, the aggregate distance matrix produced by string edit distance reveals that the great degree of phonetic continuity on the grasslands of the northeastern edge of the plateau is matched by an equal degree of phonetic discontinuity in the mountains forming the eastern border of the plateau. While the dialects located on the grasslands can be grouped together into one cluster, the dialects in the mountains can be grouped together into six clusters.

ScanGraph: A Novel Scanpath Comparison Method Using Visualisation of Graph Cliques

The article describes a new tool for analyses of eye-movement data. Many different approaches to scanpath comparison exist. One of the most frequently used approaches is String Edit Distance, where the gaze trajectories are replaced by the sequences of visited Areas of Interest. In cartographic literature, the most commonly used software for scanpath comparison is eyePatterns. During the analysis of eyePatterns functionality, we have found that tree-graph visualization of its results is not reliable. Thus, we decided to develop a new tool called ScanGraph. Its computational algorithms are modified to work better with the sequences with different lengths. The output is visualized as a simple graph, and similar groups of sequences are displayed as cliques of this graph. The article describes ScanGraph’s functionality on the example of a simple cartographic eye-tracking study. Differences of the reading strategy of a simple map between cartographic experts and novices were investigated. The paper should serve to the researchers who would like to analyze differences between groups of participants, and who would like to use our tool - ScanGraph, available at www.eyetracking.upol.cz/scangraph.