How Well Do Ontario Library Web Sites Meet New Accessibility Requirements?

New changes to Ontario law will require library web sites to comply with the Web Content Accessibility Guidelines, version 2.0 (WCAG 2.0). This study evaluates 64 Ontario university, college, and public library web sites to see how well they comply with WCAG 2.0 guidelines at present. An average of 14.75 accessibility problems were found per web page. The most common problems included invalid html, poor color contrast, incorrect form controls and labels, missing alt text, bad link text, improper use of headings, using html to format pages, using absolute units of measure, and issues with tables and embedded objects

Htab2RDF: Mapping HTML Tables to RDF Triples

The Web has become a tremendously huge data source hidden under linked documents. A significant number of Web documents include HTML tables generated dynamically from relational databases. Often, there is no direct public access to the databases themselves. On the other hand, RDF (Resource Description Framework) gives an efficient mechanism to represent directly data on the Web based on a Web-scalable architecture for identification and interpretation of terms. This leads to the concept of Linked Data on the Web. To allow direct access to data on the Web as Linked Data, we propose in this paper an approach to transform HTML tables into RDF triples. It consists of three main phases: refining, pre-treatment and mapping. The whole process is assisted by a domain ontology and the WordNet lexical database. A tool called Htab2RDF has been implemented. Experiments have been carried out to evaluate and show efficiency of the proposed approach

A clustering approach to extract data from HTML tables

HTML tables have become pervasive on the Web. Extracting their data automatically is difficult because finding the relationships between their cells is not trivial due to the many different layouts, encodings, and formats available. In this article, we introduce Melva, which is an unsupervised domain-agnostic proposal to extract data from HTML tables without requiring any external knowledge bases. It relies on a clustering approach that helps make label cells apart from value cells and establish their relationships. We compared Melva to four competitors on more than 3 000 HTML tables from the Wikipedia and the Dresden Web Table Corpus. The conclusion is that our proposal is 21.70% better than the best unsupervised competitor and equals the best supervised competitor regarding effectiveness, but it is 99.14% better regarding efficiencyMinisterio de Ciencia e Innovación PID2020-112540RB-C44Ministerio de Economía y Competitividad TIN2016-75394-RJunta de Andalucía P18-RT-106

Identifying Web Tables - Supporting a Neglected Type of Content on the Web

The abundance of the data in the Internet facilitates the improvement of extraction and processing tools. The trend in the open data publishing encourages the adoption of structured formats like CSV and RDF. However, there is still a plethora of unstructured data on the Web which we assume contain semantics. For this reason, we propose an approach to derive semantics from web tables which are still the most popular publishing tool on the Web. The paper also discusses methods and services of unstructured data extraction and processing as well as machine learning techniques to enhance such a workflow. The eventual result is a framework to process, publish and visualize linked open data. The software enables tables extraction from various open data sources in the HTML format and an automatic export to the RDF format making the data linked. The paper also gives the evaluation of machine learning techniques in conjunction with string similarity functions to be applied in a tables recognition task.Comment: 9 pages, 4 figure

Tag-Cloud Drawing: Algorithms for Cloud Visualization

Tag clouds provide an aggregate of tag-usage statistics. They are typically sent as in-line HTML to browsers. However, display mechanisms suited for ordinary text are not ideal for tags, because font sizes may vary widely on a line. As well, the typical layout does not account for relationships that may be known between tags. This paper presents models and algorithms to improve the display of tag clouds that consist of in-line HTML, as well as algorithms that use nested tables to achieve a more general 2-dimensional layout in which tag relationships are considered. The first algorithms leverage prior work in typesetting and rectangle packing, whereas the second group of algorithms leverage prior work in Electronic Design Automation. Experiments show our algorithms can be efficiently implemented and perform well.Comment: To appear in proceedings of Tagging and Metadata for Social Information Organization (WWW 2007

SWI-Prolog and the Web

Where Prolog is commonly seen as a component in a Web application that is either embedded or communicates using a proprietary protocol, we propose an architecture where Prolog communicates to other components in a Web application using the standard HTTP protocol. By avoiding embedding in external Web servers development and deployment become much easier. To support this architecture, in addition to the transfer protocol, we must also support parsing, representing and generating the key Web document types such as HTML, XML and RDF. This paper motivates the design decisions in the libraries and extensions to Prolog for handling Web documents and protocols. The design has been guided by the requirement to handle large documents efficiently. The described libraries support a wide range of Web applications ranging from HTML and XML documents to Semantic Web RDF processing. To appear in Theory and Practice of Logic Programming (TPLP)Comment: 31 pages, 24 figures and 2 tables. To appear in Theory and Practice of Logic Programming (TPLP

Algoritmos para el reconocimiento de estructuras de tablas

Tables are widely adopted to organize and publish data. For example, the Web has an enormous number of tables, published in HTML, embedded in PDF documents, or that can be simply downloaded from Web pages. However, tables are not always easy to interpret due to the variety of features and formats used. Indeed, a large number of methods and tools have been developed to interpreted tables. This work presents the implementation of an algorithm, based on Conditional Random Fields (CRFs), to classify the rows of a table as header rows, data rows or metadata rows. The implementation is complemented by two algorithms for table recognition in a spreadsheet document, respectively based on rules and on region detection. Finally, the work describes the results and the benefits obtained by applying the implemented algorithm to HTML tables, obtained from the Web, and to spreadsheet tables, downloaded from the Brazilian National Petroleum Agency.Las Tablas son una manera bien común de organizar y publicar datos. Por ejemplo, la Web posee un enorme número de tablas publicadas en HTML integradas en documentos PDF, o que pueden ser simplemente descargadas de páginas Web. Sin embargo, las tablas no siempre son fáciles de interpretar pues poseen una gran variedad de características y son organizadas en diferentes formatos. De hecho, se han desarrollado un gran número de métodos y herramientas para la interpretación de tablas. Este trabajo presenta la implementación de un algoritmo, basado en Campos Aleatorios Condicionales (CRF, Conditional Random Fields), para clasificar las filas de una tabla como fila de encabezado, fila de datos y fila metadatos. La implementación se complementa con dos algoritmos para reconocer tablas en hojas de cálculos, específicamente, basados en reglas y detección de regiones. Finalmente, el trabajo describe los resultados y beneficios obtenidos por la aplicación del algoritmo para tablas HTML, obtenidas desde la Web, y las tablas en forma de hojas de cálculo, descargadas desde el sitio Web de la Agencia Nacional de Petróleo de Brasil

A Novel Approach to Data Extraction on Hyperlinked Webpages

The World Wide Web has an enormous amount of useful data presented as HTML tables. These tables are often linked to other web pages, providing further detailed information to certain attribute values. Extracting schema of such relational tables is a challenge due to the non-existence of a standard format and a lack of published algorithms. We downloaded 15,000 web pages using our in-house developed web-crawler, from various web sites. Tables from the HTML code were extracted and table rows were labeled with appropriate class labels. Conditional random fields (CRF) were used for the classification of table rows, and a nondeterministic finite automaton (NFA) algorithm was designed to identify simple, complex, hyperlinked, or non-linked tables. A simple schema for non-linked tables was extracted and for the linked-tables, relational schema in the form of primary and foreign-keys (PK and FK) were developed. Child tables were concatenated with the parent table’s attribute value (PK), serving as foreign keys (FKs). Resultantly, these tables could assist with performing better and stronger queries using the join operation. A manual checking of the linked web table results revealed a 99% precision and 68% recall values. Our 15,000-strong downloadable corpus and a novel algorithm will provide the basis for further research in this field.publishedVersio