Program slicing by calculation

Program slicing is a well known family of techniques used to identify code fragments which depend on or are depended upon specific program entities. They are particularly useful in the areas of reverse engineering, program understanding, testing and software maintenance. Most slicing methods, usually oriented towards the imperative or object paradigms, are based on some sort of graph structure representing program dependencies. Slicing techniques amount, therefore, to (sophisticated) graph transversal algorithms. This paper proposes a completely different approach to the slicing problem for functional programs. Instead of extracting program information to build an underlying dependencies’ structure, we resort to standard program calculation strategies, based on the so-called Bird-Meertens formalism. The slicing criterion is specified either as a projection or a hiding function which, once composed with the original program, leads to the identification of the intended slice. Going through a number of examples, the paper suggests this approach may be an interesting, even if not completely general, alternative to slicing functional programs

Slicing functional programs by calculation

Program slicing is a well known family of techniques used to identify code fragments which depend on or are depended upon specific program entities. They are particularly useful in the areas of reverse engineering, program understanding, testing and software maintenance. Most slicing methods, usually targeting either the imperative or the object oriented paradigms, are based on some sort of graph structure representing program dependencies. Slicing techniques amount, therefore, to (sophisticated) graph transversal algorithms. This paper proposes a completely different approach to the slicing problem for functional programs. Instead of extracting program information to build an underlying dependencies’ structure, we resort to standard program calculation strategies, based on the so-called Bird- Meertens formalism. The slicing criterion is specified either as a projection or a hiding function which, once composed with the original program, leads to the identification of the intended slice. Going through a number of examples, the paper suggests this approach may be an interesting, even if not completely general alternative to slicing functional programs

Eigenvalue computations in the context of data-sparse approximations of integral operators

In this work, we consider the numerical solution of a large eigenvalue problem resulting from a finite rank discretization of an integral operator. We are interested in computing a few eigenpairs, with an iterative method, so a matrix representation that allows for fast matrix-vector products is required. Hierarchical matrices are appropriate for this setting, and also provide cheap LU decompositions required in the spectral transformation technique. We illustrate the use of freely available software tools to address the problem, in particular SLEPc for the eigensolvers and HLib for the construction of H-matrices. The numerical tests are performed using an astrophysics application. Results show the benefits of the data-sparse representation compared to standard storage schemes, in terms of computational cost as well as memory requirements.

Anotação ao Acórdão do Supremo Tribunal de Justiça (Português), de 25 de Janeiro de 2011 - a resolução e o contrato de franquia

É importante chamar a atenção das possíveis diferenças entre o contrato de franquia e o contrato de agência no que diz respeito também ao problema da resolução em termos mais gerais ou em termos mais concretos; 1 – Sumário do Acórdão do Supremo Tribunal de Justiça, de 25 de Janeiro de 2011; 2 – Texto completo do Acórdão do Supremo Tribunal de Justiça, de 25 de Janeiro de 2011, Juiz Conselheiro Garcia CALEJO (Relator), Juiz Conselheiro Hélder ROQUE e Juiz Conselheiro Sebastião PÓVOAS: cfr. http://www.dgsi.pt , 21 de Abril de 2011; 3 – Anotação; 3.1 – Introdução à anotação; 3.2 – A questão da resolução em termos gerais; 3.3 – A questão da resolução no «contrato atípico de franquia»; 4 – Conclusões; Abstract: is important to draw attention to potential differences between the franchise agreement and agency agreement with regard also to the resolution problem in more general terms or in more concrete terms; 1 - Summary of the Sentence of the Supreme Court of Justice, 25 of January of 2011; 2 - Complete text of the Sentence of the Supreme Court of Justice, 25 of January of 2011, Advising Judge Garcia CALEJO (Reporter), Advising Judge Hélder ROQUE and Advising Juiz Sebastião PÓVOAS: cfr. http://www.dgsi.pt , 21 of April of 2011; 3 - Notation; 3.1 - Introduction to the notation; 3.2 - The question of the resolution in general terms; 3.3 - The question of the resolution in the «atypical contract of franshise»; 4 - Conclusions;

Anotação ao Acórdão do Supremo Tribunal de Justiça (Português), de 25 de Janeiro de 2011 - a resolução e o contrato de franquia

is important to draw attention to potential differences between the franchise agreement and agency agreement with regard also to the resolution problem in more general terms or in more concrete terms; 1 - Summary of the Sentence of the Supreme Court of Justice, 25 of January of 2011; 2 - Complete text of the Sentence of the Supreme Court of Justice, 25 of January of 2011, Advising Judge Garcia CALEJO (Reporter), Advising Judge Hélder ROQUE and Advising Juiz Sebastião PÓVOAS: cfr. http://www.dgsi.pt , 21 of April of 2011; 3 - Notation; 3.1 - Introduction to the notation; 3.2 - The question of the resolution in general terms; 3.3 - The question of the resolution in the «atypical contract of franshise»; 4 - Conclusions;