Complexity Hierarchies Beyond Elementary

We introduce a hierarchy of fast-growing complexity classes and show its suitability for completeness statements of many non elementary problems. This hierarchy allows the classification of many decision problems with a non-elementary complexity, which occur naturally in logic, combinatorics, formal languages, verification, etc., with complexities ranging from simple towers of exponentials to Ackermannian and beyond.Comment: Version 3 is the published version in TOCT 8(1:3), 2016. I will keep updating the catalogue of problems from Section 6 in future revision

Categorical semantics and composition of tree transducers

In this thesis we see two new approaches to compose tree transducers and more general to fuse functional programs. The first abroach is based on initial algebras. We prove a new variant of the acid rain theorem for mutually recursive functions where the build function is substituted by a concrete functor. Moreover, we give a symmetric form (i.e. consumer and producer have the same syntactic form) of our new acid rain theorem where fusion is composition in a category and thus in particular associative. Applying this to compose top-down tree transducers yields the same result (on a syntactic level) as the classical top-down tree transducer composition. The second approach is based on free monads and monad transformers. In the same way as monoids are used in the theory of character string automata, we use monads in the theory of tree transducers. We generalize the notion of a tree transducer defining the monadic transducer, and we prove an according fusion theorem. Moreover, we prove that homomorphic monadic transducers are semantically equivalent. The latter makes it possible to compose syntactic classes of tree transducers (or particular functional programs) by simply composing endofunctors

Proceedings of JAC 2010. Journées Automates Cellulaires

The second Symposium on Cellular Automata “Journ´ees Automates Cellulaires” (JAC 2010) took place in Turku, Finland, on December 15-17, 2010. The first two conference days were held in the Educarium building of the University of Turku, while the talks of the third day were given onboard passenger ferry boats in the beautiful Turku archipelago, along the route Turku–Mariehamn–Turku. The conference was organized by FUNDIM, the Fundamentals of Computing and Discrete Mathematics research center at the mathematics department of the University of Turku. The program of the conference included 17 submitted papers that were selected by the international program committee, based on three peer reviews of each paper. These papers form the core of these proceedings. I want to thank the members of the program committee and the external referees for the excellent work that have done in choosing the papers to be presented in the conference. In addition to the submitted papers, the program of JAC 2010 included four distinguished invited speakers: Michel Coornaert (Universit´e de Strasbourg, France), Bruno Durand (Universit´e de Provence, Marseille, France), Dora Giammarresi (Universit` a di Roma Tor Vergata, Italy) and Martin Kutrib (Universit¨at Gie_en, Germany). I sincerely thank the invited speakers for accepting our invitation to come and give a plenary talk in the conference. The invited talk by Bruno Durand was eventually given by his co-author Alexander Shen, and I thank him for accepting to make the presentation with a short notice. Abstracts or extended abstracts of the invited presentations appear in the first part of this volume. The program also included several informal presentations describing very recent developments and ongoing research projects. I wish to thank all the speakers for their contribution to the success of the symposium. I also would like to thank the sponsors and our collaborators: the Finnish Academy of Science and Letters, the French National Research Agency project EMC (ANR-09-BLAN-0164), Turku Centre for Computer Science, the University of Turku, and Centro Hotel. Finally, I sincerely thank the members of the local organizing committee for making the conference possible. These proceedings are published both in an electronic format and in print. The electronic proceedings are available on the electronic repository HAL, managed by several French research agencies. The printed version is published in the general publications series of TUCS, Turku Centre for Computer Science. We thank both HAL and TUCS for accepting to publish the proceedings.Siirretty Doriast

Mindedness: On the minimal conditions for possessing a mind

This thesis explores the grounds for justifying the ascription of mentality to non-human agents. In the first part, I set my research within the framework of scientific naturalism and the computational theory of mind. Then I argue that while the behaviour of certain agents demands a computational explanation, there is no justification for attributing mentality to them. I use these examples to backup my claim that some authors indulge in unnecessary ascription of mentality to certain animals (e.g. insects) on the main grounds that they possess computational capacities. The second part of my thesis takes up recent literature exploring the line that divides computational agents with and without mentality. More precisely, I criticise the proposals put forward by Fodor, Dretske, Burge, Bermúdez and Carruthers. My main argument takes the form of a reductio ad absurdum by showing that their criteria apply to artefacts to which the attribution of mentality is unjustified. Overall, I conclude that even though the views advanced by the mentioned authors help to elucidate the computational grounds that could make the emergence of a mind possible, they do not offer a satisfactory criterion for the ascription of mentality to some computational agents but not others. In the final part I develop my own proposal for grounding the attribution of mentality. My strategy consists in drawing upon the distinction between personal and subpersonal levels of explanation, according to which properly psychological descriptions have whole-agents as their subject matter, use a distinctive theoretical vocabulary, and are constrained by norms of rationality. After showing that the personal-subpersonal distinction is compatible with a naturalistic framework, I adapt the distinction so that it can be applied to non-human agents, and conclude that it imposes constraints in cognitive architecture that point in the direction of cognitive access, generality and integration

Acoustic and Elastic Waves: Recent Trends in Science and Engineering

The present Special Issue intends to explore new directions in the field of acoustics and ultrasonics. The interest includes, but is not limited to, the use of acoustic technology for condition monitoring of materials and structures. Topics of interest (among others): • Acoustic emission in materials and structures (without material limitation) • Innovative cases of ultrasonic inspection • Wave dispersion and waveguides • Monitoring of innovative materials • Seismic waves • Vibrations, damping and noise control • Combination of mechanical wave techniques with other types for structural health monitoring purposes. Experimental and numerical studies are welcome

Exploring the design space of metadata-focused file management systems

Operating systems both old and new are reliant on the venerable hierarchical file system. For some time now, however, attempts have been made to either define new file systems or to bolt on applications that offer much improved functionality to attach and use metadata. This is because researchers have shown that traditional file systems are not able to meet users' needs in terms of organising large numbers of files effectively, and to support expeditious retrieval of those files when they are needed at a later time. Numerous proposals for post-hierarchical file management systems have been described in the literature; researchers focus on different dimensions of such systems in order to solve or reduce identified limitations. In some cases this leads to significantly different file system architectures, while in other cases new functionality is added on top of a traditional system through special purpose user-space applications. Orthogonally, some proposals focus on tags while others favour named attribute-value pairs. Still other choices are, seemingly, made in an ad hoc and often implicit manner. This paper investigates the different dimensions and associated choices that participate in the proposal of new approaches and that affect their ability to improve on current systems. The Cartesian product of those dimensions and options forms a large design space; we map some of the existing literature onto that design space and discuss approaches to evaluate new proposals