Database Queries that Explain their Work

Provenance for database queries or scientific workflows is often motivated as providing explanation, increasing understanding of the underlying data sources and processes used to compute the query, and reproducibility, the capability to recompute the results on different inputs, possibly specialized to a part of the output. Many provenance systems claim to provide such capabilities; however, most lack formal definitions or guarantees of these properties, while others provide formal guarantees only for relatively limited classes of changes. Building on recent work on provenance traces and slicing for functional programming languages, we introduce a detailed tracing model of provenance for multiset-valued Nested Relational Calculus, define trace slicing algorithms that extract subtraces needed to explain or recompute specific parts of the output, and define query slicing and differencing techniques that support explanation. We state and prove correctness properties for these techniques and present a proof-of-concept implementation in Haskell.Comment: PPDP 201

EM BUSCA DOS PRINCÍPIOS DA GESTÃO DA QUALIDADE TOTAL EM SERVIÇOS DE PROJETO DE ARQUITETURA: DESTAQUES DA TURQUIA

Proposal: Architectural design companies increasingly recognize that time spent on management is not at the expense of their production and there are always better ways to organize business. Although architects have long placed a traditional emphasis on quality, quality management is still a new concept for the majority of architectural design companies, which have to organize relatively more complicated operations nowadays to meet their clients’ expectations. This study aims to understand how architectural design companies define quality and explores the extent to which Total Quality Management (TQM) principles like continual improvement, employee involvement, customer satisfaction and others can be pertinent in these companies. Adopting a qualitative research strategy, the authors interviewed with the owner-managers of 10 widely-recognized architectural design companies of different size in Istanbul. The results from the content analysis of semi-structured interview data suggest that i) TQM principles cannot be directly applied in architectural design companies without an appropriate translation; ii) special characteristics of design services are important to explain quality-related perceptions of owner-managers; iii) the owner-managers feel the pressure from the changing internal and external environmental conditions, however few of them adopt a systematic and documented approach to quality management. Architectural design offices which aim to establish a quality management system can benefit from this study to understand potential problem areas on their road.As empresas de projeto de arquitetura cada vez mais reconhecem que o tempo dedicado à gestão não onera a sua produção e que há sempre maneiras de organizar melhor as atividades empresariais. Embora arquitetos tenham colocado durante muito tempo uma ênfase tradicional na qualidade, a gestão da qualidade ainda é um conceito novo para a maioria das empresas de projeto de arquitetura, que, hoje em dia, têm de organizar operações relativamente mais complicadas para atender às expectativas de seus clientes. Este estudo visa compreender de que modo as empresas de projeto de arquitetura definem qualidade e exploram os limites nos quais os princípios da gestão da qualidade total (TQM), como melhoria contínua, envolvimento dos funcionários, satisfação do cliente e outros, podem ser pertinentes para essas empresas. Adotando uma estratégia de pesquisa qualitativa, os autores entrevistaram os proprietários-gerentes de 10 empresas de projeto de arquitetura amplamente reconhecidas, de diferentes tamanhos, em Istambul. Os resultados da análise de conteúdo dos dados de entrevistas semi-estruturadas sugerem que: i) os princípios do TQM não podem ser aplicados diretamente em empresas de projeto de arquitetura, sem uma tradução adequada; ii) as características especiais dos serviços de projeto são importantes para explicar as percepções de proprietários-gerentes relacionadas à qualidade; iii) os proprietários-gerentes sentem a pressão da mudança interna e externa das condições ambientais, porém poucos deles adotam uma abordagem sistemática e documentada para a gestão da qualidade. Empresas de projeto de arquitetura que têm como objetivo estabelecer um sistema de gestão da qualidade podem se beneficiar deste estudo para conhecer as áreas potencialmente problemáticas que encontrarão

Brief Announcement: Parallel Dynamic Tree Contraction via Self-Adjusting Computation

International audienceDynamic algorithms are used to compute a property of some data while the data undergoes changes over time. Many dynamic algorithms have been proposed but nearly all are sequential. In this paper, we present our ongoing work on designing a parallel algorithm for the dynamic trees problem, which requires computing a property of a forest as the forest undergoes changes. Our algorithm allows insertion and/or deletion of both vertices and edges anywhere in the input and performs updates in parallel. We obtain our algorithm by applying a dynamization technique called self-adjusting computation to the classic algorithm of Miller and Reif for tree contraction