# Workshop on Descriptional and Computational Complexity of Formal Languages

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# Talk by José Nuno Oliveira, September 19, 14:30

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Title: Software components as monadic, weighted Mealy machines in typed linear algebra

Speaker: José Nuno Oliveira (Universidade do Minho)

Time: September 19, 14:30

Place: S1, DCC-FCUP

Abstract:

The propagation of faults in component-based software (CBS) systems is a relevant topic in current research on software architecture and software certification. However, traditional CBS programming considers risk evaluation a posteriori, once the implemented software is subject to fault injection and other simulation techniques. In this talk we advocate that risk of failure be considered at the early stages of the design using a number of combinators which includes probabilistic choice between 'good' and 'bad' behaviour. Such combinators are implemented in Haskell on top of a probabilistic functional programming library, which makes it possible to animate and simulate faults and their propagation. Their quantitative semantics is expressed in the adjoint category of left stochastic matrices, using matrix point-free notation and calculus. This makes it possible to "internalize" the quantitative semantics of (faulty) components just by changing from the category of sets to suitable categories of matrices, while retaining the original formulae. The main difference resides in the weakness of products in the latter and absence of 'uniform copying operations', which makes one's life harder compared to the original coalgebraic component calculus - a subject of on-going research. (Joint work with L.S. Barbosa.)

José Nuno Oliveira is a professor at the Department of Informatics, School of Engineering of University of Minho in Portugal. His research interests include formal methods, algebra of programming and program calculation, and functional programming. He aims at improving scientific standards in software design through formal methods and calculational techniques. These include the application of mathematical transforms in refactoring and improving existing software theories.

# WORDS 2013

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The paper “On Strongly Connected Ideal Languages” by Emanuele Rodaro and Rogério Reis will be presented at WORDS 2013.

The 9th International Conference on Words will be held at the Department of Mathematcs of the University of Turku (Finland) on September 16-20 2013.

# CIAA 2013

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The paper “Incomplete Transition Complexity of Basic Operations on Finite Languages” by Eva Maia, Nelma Moreira and Rogério Reis will be presented at CIAA 2013.

The 17th International Conference on Implementation and Application of Automata will be held at the Saint Mary's University, Halifax, Nova Scotia, Canada. on August 16-19 2013.

# David Pereira's PhD

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David Pereira defended his PhD thesis entitled “Towards Certified Program Logics for the Verification of Imperative Programs” on April, 19 of 2013.