Constructive Proofs or Constructive Statements?

A question raised at previous MAP meetings is the following. Is Sergeraert\u27s "Constructive Algebraic Topology" (CAT, in short) really constructive (in the strict logical sense of the word "constructive")? We have not an answer to that question, but we are interested in the following: could have a positive (or negative) answer to the previous question an influence in the problem of proving the correctness of CAT programs (as Kenzo)? Studying this problem, we have observed that, in fact, many CAT programs can be extracted from the statements (that is, from the specification of certain objects and constructions), without needing an extraction from proofs. This remark shows that the logic used in the proofs is uncoupled with respect to the correctness of programs. Thus, the first question posed could be quite irrelevant from the practical point of view. These rather speculative ideas will be illustrated by means of some elementary examples, where the Isabelle code extraction tool can be successfully applied

Integrating multiple sources to answer questions in Algebraic Topology

We present in this paper an evolution of a tool from a user interface for a concrete Computer Algebra system for Algebraic Topology (the Kenzo system), to a front-end allowing the interoperability among different sources for computation and deduction. The architecture allows the system not only to interface several systems, but also to make them cooperate in shared calculations.Comment: To appear in The 9th International Conference on Mathematical Knowledge Management: MKM 201

Situación económica de los periódicos de información deportiva en España. Análisis del impacto de las nuevas tecnologías en sus cifras de negocio

A study of sport newspapers main indicators shows that they at present fare better than conventional information newspapers. This paper also provides a new indicator: the average reading frequency that shows us the relevance that readers attach to sport newspapers. Throughout the paper a statistical database is afforded in order to establish the relationship between online readers and the development of Information Society. The study also offers a statistical relationship between the diminishing diffusion indexes of pay printed newspapers and the changing percentages of readers of online newspapersEl análisis de sus principales cifras económicas muestra que los periódicos deportivos atraviesan una mejor situación respecto a los periódicos de información general. Asimismo, en este artículo se construye un nuevo indicador: la frecuencia media de lectura, que pone de manifiesto la relevancia que asignan sus lectores a los periódicos deportivos. En la exposición se realiza un análisis estadístico de la relación existente entre el número de lectores online de los periódicos y el grado de desarrollo de la Sociedad de la Información. También se estudia la relación estadística entre las disminuciones de los índices de difusión de los periódicos impresos de pago y las variaciones de los porcentajes de los lectores online de los periódicos

La demanda de los periódicos impresos y online: un análisis económico

Se está produciendo un cambio en las pautas de consumo de los periódicos impresos, con una continua reducción del número de lectores más jóvenes, por otra parte las nuevas tecnologías están acelerando este proceso de cambio. Los jóvenes acuden a Internet en su demanda de noticias, y es además cada vez mayor el público de otras edades y de distintas clases sociales que también acude a la Red con este mismo objetivo. En Internet los periódicos online no sólo tienen que competir con las web de los otros medios, sino también con otros proveedores online de noticias.A change is taking place in the consumption patterns of printed newspapers, to the extent that a steady decline of customers is the trend, especially as regards the younger strata, and th widespread use of new technologies acts as a reinforcing factor in these changing habits. Young people use internet in order to supply their news demand, and this is also the means that other age groups and people from different social strata are taking advantage of. In Internet newspapers on-line must not only compete with the web-sites of other news media but also with other news providers