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  • 101.
    Björklund, Henrik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Drewes, Frank
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Ericson, Petter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Between a Rock and a Hard Place: Parsing for Hyperege Replacement DAG Grammars2016Inngår i: Proc. 10th International Conference on Language and Automata Theory and Applications (LATA 2016) / [ed] A.H. Dediu, J. Janoušek, C. Martín-Vide, and B. Truthe, Springer Publishing Company, 2016, Vol. 9618, s. 521-532Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Motivated by applications in natural language processing, we study the uniform membership problem for hyperedge-replacement grammars that generate directed acyclic graphs. Our major result is a low-degree polynomial-time algorithm that solves the uniform membership problem for a restricted type of such grammars. We motivate the necessity of the restrictions by two different NP-completeness results.

  • 102.
    Björklund, Henrik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Drewes, Frank
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Ericson, Petter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Parsing Weighted Order-Preserving Hyperedge Replacement Grammars2019Inngår i: Proceedings of the 16th Meeting on the Mathematics of Language / [ed] F. Drewes, P. de Groote, G. Penn, Association for Computational Linguistics, 2019, s. 1-11Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We introduce a weighted extension of the recently proposed notion oforder-preserving hyperedge-replacement grammars and prove that the weightof a graph according to such a weighted graph grammar can be computeduniformly in quadratic time (under assumptions made precise in the paper).

  • 103.
    Björklund, Henrik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Drewes, Frank
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Ericson, Petter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Parsing Weighted Order-Preserving Hyperedge Replacement Grammars2018Rapport (Annet vitenskapelig)
    Abstract [en]

    We introduce a weighted extension of the recently proposed notion of order-preserving hyperedge-replacement grammars and prove that the weight of a graph according to such a weighted graph grammar can be computed uniformly in quadratic time (under assumptions made precise in the paper).

  • 104.
    Björklund, Henrik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Drewes, Frank
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Ericson, Petter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Starke, Florian
    Faculty of Computer Science, TU Dresden.
    Uniform Parsing for Hyperedge Replacement Grammars2018Rapport (Annet vitenskapelig)
    Abstract [en]

    It is well known that hyperedge-replacement grammars can generate NP-complete graph languages even under seemingly harsh restrictions. This means that the parsing problem is difficult even in the non-uniform setting, in which the grammar is considered to be fixed rather than being part of the input. Little is known about restrictions under which truly uniform polynomial parsing is possible. In this paper we propose a low-degree polynomial-time algorithm that solves the uniform parsing problem for a restricted type of hyperedge-replacement grammars which we expect to be of interest for practical applications.

  • 105.
    Björklund, Henrik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Ericson, Petter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    A note on the complexity of deterministic tree-walking transducers2013Inngår i: Non-Classical Models of Automata and Applications (NCMA 2013), Österreichische Computer Gesellschaft , 2013Konferansepaper (Fagfellevurdert)
  • 106.
    Björklund, Henrik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Gelade, Wouter
    Marquardt, Marcel
    Martens, Wim
    Incremental XPath Evaluation2009Inngår i: Proceedings of the 12th international conference on database theory: March 23-25, 2009, Saint Petersbourgh, Russia / [ed] Ronald Fagin, 2009, s. 162-173Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We study the problem of incrementally maintaining an XPath query on an XML database under updates. The updates we consider are node insertion, node deletion, and node relabeling. Our main results are that downward XPath queries can be incrementally maintained in time O(depth(D) · poly(Q)) and conjunctive forward XPath queries in time O(depth(D)· log(width(D))·poly(Q)), where D is the size of the database, Q the size of the query, and depth(D) and width(D) are the nesting depth and maximum number of siblings in the database, respectively. The auxiliary data structures for maintenance are linear in D and polynomial in Q in all these cases.

  • 107.
    Björklund, Henrik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Martens, Wim
    The tractability frontier for NFA minimization2012Inngår i: Journal of computer and system sciences (Print), ISSN 0022-0000, E-ISSN 1090-2724, Vol. 78, nr 1, s. 198-210Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We prove that minimizing finite automata is NP-hard for almost all classes of automata that extend the class of deterministic finite automata. More specifically, we show that minimization is NP-hard for all finite automata classes that subsume the class of δNFAs which accept strings of length at most three. Here, δNFAs are the finite automata that are unambiguous, allow at most one state q with a non-deterministic transition for at most one alphabet symbol a, and are allowed to visit state q at most once in a run. As a corollary, we also obtain that the same result holds for all finite automata classes that subsume that class of finite automata that are unambiguous, have at most two initial states, and accept strings of length at most two.

  • 108.
    Björklund, Henrik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Martens, Wim
    Schweikardt, Nicole
    Schwentick, Thomas
    Logik und Automaten: Ein echtes Dreamteam2010Inngår i: Informatik-Spektrum, ISSN 0170-6012, E-ISSN 1432-122X, Vol. 33, nr 5, s. 452-461Artikkel, forskningsoversikt (Annet (populærvitenskap, debatt, mm))
  • 109.
    Björklund, Henrik
    et al.
    Technical University of Dortmund, Germany.
    Martens, Wim
    Technical University of Dortmund, Germany.
    Schwentick, Thomas
    Technical University of Dortmund, Germany.
    Conjunctive query containment over trees2011Inngår i: Journal of computer and system sciences (Print), ISSN 0022-0000, E-ISSN 1090-2724, Vol. 77, nr 3, s. 450-472Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The complexity of containment and satisfiability of conjunctive queries over finite, unranked, labeled trees is studied with respect to the axes ChildNextSibling, their transitive and reflexive closures, andFollowing. For the containment problem a trichotomy is presented, classifying the problems as in PTIME, coNP-complete, or -complete. For the satisfiability problem most problems are classified as either in PTIME or NP-complete.

  • 110.
    Björklund, Henrik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Martens, Wim
    Schwentick, Thomas
    Conjunctive query containment over trees using schema information2018Inngår i: Acta Informatica, ISSN 0001-5903, E-ISSN 1432-0525, Vol. 55, nr 1, s. 17-56Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We study the containment, satisfiability, and validity problems for conjunctive queries over trees with respect to a schema. We show that conjunctive query containment and validity are 2EXPTIME -complete with respect to a schema, in both cases where the schema is given as a DTD or as a tree automaton. Furthermore, we show that satisfiability for conjunctive queries with respect to a schema can be decided in NP . The problem is NP -hard already for queries using only one kind of axis. Finally, we consider conjunctive queries that can test for equalities and inequalities of data values. Here, satisfiability and validity are decidable, but containment is undecidable, even without schema information. On the other hand, containment with respect to a schema becomes decidable again if the "larger" query is not allowed to use both equalities and inequalities.

  • 111.
    Björklund, Henrik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Martens, Wim
    University of Bayreuth.
    Schwentick, Thomas
    Technical University of Dortmund.
    Validity of Tree Pattern Queries with Respect to Schema Information2013Inngår i: Mathematical Foundations of Computer Science 2013: 38th International Symposium, MFCS 2013, Klosterneuburg, Austria, August 26-30, 2013. Proceedings / [ed] Krishnendu Chatterjee, Jiri Sgall, Springer: Springer Berlin/Heidelberg, 2013, s. 171-182Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We prove that various containment and validity problems for tree pattern queries with respect to a schema are EXPTIME-complete. When one does not require the root of a tree pattern query to match the root of atree, validity of a non-branching tree pattern query with respect to a Relax NG schema or W3C XML Schema is already EXPTIME-hard when the query does not branch and uses only child axes. These hardness results already hold when the alphabet size is fixed. Validity with respect to a DTD is proved to be EXPTIME-hard already when the query only uses child axes and is allowed to branch only once.

  • 112.
    Björklund, Henrik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Martens, Wim
    Universität Bayreuth.
    Timm, Thomas
    Universität Bayreuth.
    Efficient incremental evaluation of succinct regular expressions2015Inngår i: Proceedings of the 24th ACM International on Conference on Information and Knowledge Management, Association for Computing Machinery (ACM), 2015, s. 1541-1550Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Regular expressions are omnipresent in database applications. They form the structural core of schema languages for XML, they are a fundamental ingredient for navigational queries in graph databases, and are being considered in languages for upcoming technologies such as schema- and transformation languages for tabular data on the Web. In this paper we study the usage and effectiveness of the counting operator (or: limited repetition) in regular expressions. The counting operator is a popular extension which is part of the POSIX standard and therefore also present in regular expressions in grep, Java, Python, Perl, and Ruby. In a database context, expressions with counting appear in XML Schema and languages for querying graphs such as SPARQL 1.1 and Cypher.

    We first present a practical study that suggests that counters are extensively used in practice. We then investigate evaluation methods for such expressions and develop a new algorithm for efficient incremental evaluation. Finally, we conduct an extensive benchmark study that shows that exploiting counting operators can lead to speed-ups of several orders of magnitude in a wide range of settings: normal and incremental evaluation on synthetic and real expressions.

  • 113.
    Björklund, Henrik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Schuster, Martin
    Technische Universität Dortmund.
    Schwentick, Thomas
    Technische Universität Dortmund.
    Kulbatzki, Joscha
    SCISYS Deutschland GmbH.
    On optimum left-to-right strategies for active context-free games2013Inngår i: ICDT '13 Proceedings of the 16th International Conference on Database Theory, ACM Press, 2013, s. 105-116Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Active context-free games are two-player games on strings over finite alphabets with one player trying to rewrite the input string to match a target specification. These games have been investigated in the context of exchanging Active XML (AXML) data. While it was known that the rewriting problem is undecidable in general, it is shown here that it is EXPSPACE-complete to decide for a given contextfree game, whether all safely rewritable strings can be safely rewritten in a left-to-right manner, a problem that was previously considered by Abiteboul et al. Furthermore, it is shown that the corresponding problem for games with finite replacement languages is EXPTIME-complete.

  • 114.
    Björklund, Henrik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Schwentick, Thomas
    On notions of regularity for data languages2010Inngår i: Theoretical Computer Science, ISSN 0304-3975, E-ISSN 1879-2294, Vol. 411, nr 4-5, s. 702-715Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    With motivation from considerations in XML database theory and model checking, data strings have been introduced as an extension of finite alphabet strings which carry, at each position, a symbol and a data value from an infinite domain. Previous work has shown that it is difficult to come up with an expressive yet decidable automaton model for data languages. Recently, such a model, data automata, was introduced. This paper introduces a simpler but equivalent model and investigates its expressive power, algorithmic and closure properties, and some extensions.

  • 115.
    Björklund, Johanna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Cleophas, Loek
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Department of Information Science, Stellenbosch University, Stellenbosch, South Africa.
    Minimization of Finite State Automata Through Partition Aggregation2017Inngår i: Language and Automata Theory and Applications: 11th International Conference, LATA 2017, Umeå, Sweden, March 6-9, 2017, Proceedings / [ed] Drewes, F Martin-Vide, C Truthe, B, Springer International Publishing AG , 2017, s. 223-235Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present a minimization algorithm for finite state automata that finds and merges bisimulation-equivalent states, identified through partition aggregation. We show the algorithm to be correct and run in time O(n(2)d(2) vertical bar Sigma vertical bar), where n is the number of states of the input automaton M, d is the maximal outdegree in the transition graph for any combination of state and input symbol, and vertical bar Sigma vertical bar is the size of the input alphabet. The algorithm is slower than those based on partition refinement, but has the advantage that intermediate solutions are also language equivalent to M. As a result, the algorithm can be interrupted or put on hold as needed, and the derived automaton is still useful. Furthermore, the algorithm essentially searches for the maximal model of a characteristic formula for M, so many of the optimisation techniques used to gain efficiency in SAT solvers are likely to apply.

  • 116.
    Björklund, Johanna
    et al.
    Umeå universitet.
    Cohen, Shay B.
    University of Edinburgh.
    Drewes, Frank
    Umeå universitet.
    Satta, Giorgio
    University of Padova.
    Bottom-Up Unranked Tree-to-Graph Transducers for Translation into Semantic Graphs2019Inngår i: Proceedings of the 14th International Conference on Finite-State Methods and Natural Language Processing / [ed] Heiko Vogler, Andreas Maletti, Association for Computational Linguistics, 2019, s. 7-17, artikkel-id W19-3104Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We propose a formal model for translating unranked syntactic trees, such as dependency trees, into semantic graphs. These tree-to-graph transducers can serve as a formal basis of transition systems for semantic parsing which recently have been shown to perform very well, yet hitherto lack formalization. Our model features "extended" rules and an arc-factored normal form, comes with an efficient translation algorithm, and can be equipped with weights in a straightforward manner.

  • 117.
    Björklund, Johanna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Drewes, Frank
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Jonsson, Anna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    A Comparison of Two N-Best Extraction Methods for Weighted Tree Automata2018Inngår i: Implementation and Application of Automata: 23rd International Conference, CIAA 2018, Charlottetown, PE, Canada, July 30 – August 2, 2018, Proceedings, Springer, 2018, s. 197-108Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We conduct a comparative study of two state-of-the-art al- gorithms for extracting the N best trees from a weighted tree automaton (wta). The algorithms are Best Trees, which uses a priority queue to structure the search space, and Filtered Runs, which is based on an algorithm by Huang and Chiang that extracts N best runs, implemented as part of the Tiburon wta toolkit. The experiments are run on four data sets, each consisting of a sequence of wtas of increasing sizes. Our conclusion is that Best Trees can be recommended when the input wtas exhibit a high or unpredictable degree of nondeterminism, whereas Filtered Runs is the better option when the input wtas are large but essentially deterministic.

  • 118.
    Björklund, Johanna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Drewes, Frank
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Jonsson, Anna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Finding the N Best Vertices in an Infinite Weighted Hypergraph2017Inngår i: Theoretical Computer Science, ISSN 0304-3975, E-ISSN 1879-2294, Vol. 682, s. 78s. 30-41Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We propose an algorithm for computing the N best vertices in a weighted acyclic hypergraph over a nice semiring. A semiring is nice if it is finitely-generated, idempotent, and has 1 as its minimal element. We then apply the algorithm to the problem of computing the N best trees with respect to a weighted tree automaton, and complement theoretical correctness and complexity arguments with experimental data. The algorithm has several practical applications in natural language processing, for example, to derive the N most likely parse trees with respect to a probabilistic context-free grammar. 

  • 119.
    Björklund, Johanna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Drewes, Frank
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Jonsson, Anna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    On the N best problem for hypergraphs2016Inngår i: / [ed] A. Maletti, 2016Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    We propose an algorithm for computing the $N$ best roots of a weighted hypergraph, in which the weight function is given over an idempotent and multiplicatively monotone semiring. We give a set of conditions that ensures that the weight function is well-defined and that solutions exist. Under these conditions, we prove that the proposed algorithm is correct.  This generalizes a previous result for weighted tree automata, and in doing so, broadens the practical applications.

  • 120.
    Björklund, Johanna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Drewes, Frank
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Satta, Giorgio
    University of Padova, Italy.
    Z-Automata for Compact and Direct Representation of Unranked Tree Languages2019Inngår i: Implementation and Application of Automata: 24th International Conference, CIAA 2019 Košice, Slovakia, July 22–25, 2019, Proceedings / [ed] Michal Hospodár, Galina Jirásková, Springer, 2019, s. 83-94Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Unranked tree languages are valuable in natural language processing for modelling dependency trees. We introduce a new type of automaton for unranked tree languages, called Z-automaton, that is tailored for this particular application. The Z-automaton offers a compact form of representation, and unlike the closely related notion of stepwise automata, does not require a binary encoding of its input. We establish an arc-factored normal form, and prove the membership problem of Z-automata in normal form to be in O(mn), where m is the size of the transition table of the Z-automaton and n is the size of the input tree.

  • 121.
    Björklund, Johanna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Drewes, Frank
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Zechner, Niklas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    An efficient best-trees algorithm for weighted tree automata over the tropical semiring2015Inngår i: Proc. 9th International Conference on Language and Automata Theory and Applications / [ed] Adrian-Horia Dediu, Enrico Formenti, Carlos Martín-Vide, and Bianca Truthe, Springer, 2015, s. 97-108Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We generalise a search algorithm by Mohri and Riley from strings to trees. The original algorithm takes as input a weighted automaton M over the tropical semiring, together with an integer N, and outputs N strings of minimal weight with respect to M. In our setting, M defines a weighted tree language, again over the tropical semiring, and the output is a set of N trees with minimal weight. We prove that the algorithm is correct, and that its time complexity is a low polynomial in N and the relevant size parameters of M.

  • 122.
    Björklund, Johanna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Drewes, Frank
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Zechner, Niklas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Efficient enumeration of weighted tree languages over the tropical semiring2019Inngår i: Journal of computer and system sciences (Print), ISSN 0022-0000, E-ISSN 1090-2724, Vol. 104, s. 78s. 119-130Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We generalise a search algorithm by Mohri and Riley from strings to trees. The original algorithm takes as input a nondeterministic weighted automaton M over the tropical semiring and an integer N, and outputs N strings of minimal weight with respect to M. In our setting, M is a weighted tree automaton, again over the tropical semiring, and the output is a set of N trees with minimal weight in this language. We prove that the algorithm is correct, and that its time complexity is a low polynomial in N and the relevant size parameters of M. 

  • 123.
    Blum, Johannes
    et al.
    University of Würzburg.
    Drewes, Frank
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Language Theoretic Properties of Regular DAG Languages2019Inngår i: Information and Computation, ISSN 0890-5401, E-ISSN 1090-2651, Vol. 265, s. 78s. 57-76Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We study sets of directed acyclic graphs, called regular DAG languages, which are accepted by a recently introduced type of DAG automata motivated by current developments in natural language processing. We prove (or disprove) closure properties, establish pumping lemmata, characterize finite regular DAG languages, and show that "unfolding" turns regular DAG languages into regular tree languages, which implies a linear growth property and the regularity of the path languages of regular DAG languages. Further, we give polynomial decision algorithms for the emptiness and finiteness problems, and show that deterministic DAG automata can be minimized and tested for equivalence in polynomial time.

  • 124.
    Blum, Johannes
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Drewes, Frank
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Properties of Regular DAG Languages2016Inngår i: Proc. 10th International Conference on Language and Automata Theory and Applications (LATA 2016) / [ed] A.H. Dediu, J. Janoušek, C. Martín-Vide, and B. Truthe, Springer Publishing Company, 2016, s. 427-438Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A DAG is a directed acyclic graph. We study the properties of DAG automata and their languages, called regular DAG languages. In particular, we prove results resembling pumping lemmas and show that the finiteness problem for regular DAG languages is in P.

  • 125.
    Bodin, Kenneth
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N).
    Lacoursière, Claude
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N).
    Servin, Martin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Constraint Fluids2012Inngår i: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506, Vol. 18, nr 3, s. 516-526Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a fluid simulation method whereincompressibility is enforced through a holonomic constrainton the mass density. The method starts in aLagrangian particle formulation where the mass densityand other field quantities are represented by SmoothedParticle Hydrodynamics (SPH) kernel approximations.The density constraint is formulated as a regularizedmanybody constraint and is equivalent to very highsound speed. The system is integrated using a variationaldiscrete-time scheme, SPOOK, that includesconstraint regularization and stabilization. This constraintformulation of SPH enables systematic multiphysicsintegration, between rigid multibody physicsand fluids, where buoyancy falls out naturally. The fluidmodel results in a linear system of equations, whilemore general multiphysics systems result in a mixedlinear complementarity problem (MLCP) and we solvethese using iterative methods. The results demonstratenear perfect incompressibility, vastly improved stability,allowing for large time steps, and two orders of magnitudeimproved computational performance. Proof ofconcept is given for computer graphics applications andinteractive simulations.

  • 126.
    Bohlin, Victor
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Institutionen för datavetenskap.
    Visual Special Relativity2010Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Albert Einstein predicted in 1905 with his paper on special relativity the signi cantvisual eects of objects moving close to the speed of light. Einstein could not see them then but with todays graphical hardware it is possible to produce these eects in real time in a computer simulation. In this thesis the implementation, results and comparison of two techniques for doing this are presented. The two techniques dier substantially in how they execute the task. One alters the vertex positions of the objects and the other performs the eects as a post process step using a cube map. The results of the two techniques are generally the same,both having dierent advantages and disadvantages.

  • 127.
    Boketoft, Carl-Ola
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Institutionen för datavetenskap.
    Web Content ManagementSystem Powered by Ajax2010Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This master thesis is about the development of a web site for three restaurants in South Korea. For the maintenance and updating of the contents of the web site a CMS (Content Management System) was developed. The major part of the work was conducted in South Korea and in close collaboration with the owners of the restaurants in order to improve communication possibilities and to be able to gather materials for the project.A theoretical study was conducted to acquire knowledge about the web development technique Ajax, both from a programming view and how to use it for improving usability of the web site functions.From the results of the theoretical study, methods were chosen and applied into a detailed conceptual model of the web site. This model was used as a base for the implementation of the web site pages and content management functions.The resulting implementation of the web site is based on a common structure for the dierent pages, with contents available in both English and Korean. The updating of the contents is done by Ajax enhanced functions in the CMS, which also contains functions for image uploading, text editing, and layout management.

  • 128. Brasselet, Romain
    et al.
    Johansson, Roland S
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Arleo, Angelo
    Isometric coding of spiking haptic signals by peripheral somatosensory2011Inngår i: Advances in Computational Intelligence: 11th international work-conference on artificial neural networks, IWANN 2011, Torremolinos-Málaga, Spain, June 8-10, 2011, Proceedings, Part I / [ed] Cabestany, J; Rojas, I; Joya, G, Berlin: Springer Berlin/Heidelberg, 2011, s. 528-536Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We study how primary tactile afferents encode relevant contact features to mediate early processing of haptic information. In this paper, we apply metrical information theory to perform temporal decoding of human microneurography data. First, we enrich the theory by deriving a novel spike train metrics inspired by neuronal computation. This spike train metrics can be interpreted biologically and its behaviour is not influenced by spontaneous activity, which decreases the ability of other spike metrics to separate input patterns. Second, we employ our metrical information tools to demonstrate that primary spiking signals allow a putative neural decoder to go beyond stimulus discrimination. They transmit information about geometrical properties of the input space. We show that first-spike latencies are enough to guarantee maximum information transmission of tactile stimuli. However, entire primary spike trains are necessary to encode isometric representations of the stimulus space, a likely basis for generalisation in haptic perception.

  • 129. Breitgand, D.
    et al.
    Maraschini, A.
    Tordsson, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Policy-Driven Service Placement Optimization in Federated Clouds2011Rapport (Annet vitenskapelig)
    Abstract [en]

    Efficient provisioning of elastic services constitutes a significant management challenge for cloud computing providers. We consider a federated cloud paradigm, where one cloud can subcontract workloads to partnering clouds to meet peaks in demand without costly over-provisioning. We propose a model for service placement in federated clouds to maximize profit while protecting Quality of Service (QoS) as specified in the Service Level Agreements (SLA) of the workloads. Our contributions include an Integer Linear Program (ILP) formulation of the generalized federated placement problem and application of this problem to load balancing and consolidation within a cloud, as well as for cost minimization for remote placement in partnering clouds. We also provide a 2-approximation algorithm based on a greedy rounding of a Linear Program (LP) relaxation of the problem. We implement our proposed approach in the context of the RESERVOIR architecture.

  • 130. Brush, Eleanor
    et al.
    Brännström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. Evolution and Ecology Program, International Institute for Applied Systems Analysis, Laxenburg, Austria.
    Dieckmann, Ulf
    Indirect reciprocity with negative assortment and limited information can promote cooperation2018Inngår i: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 443, s. 56-65Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cooperation is ubiquitous in biological and social systems, even though cooperative behavior is often costly and at risk of exploitation by non-cooperators. Several studies have demonstrated that indirect reciprocity, whereby some members of a group observe the behaviors of their peers and use this information to discriminate against previously uncooperative agents in the future, can promote prosocial behavior. Some studies have shown that differential propensities of interacting among and between different types of agents (interaction assortment) can increase the effectiveness of indirect reciprocity. No previous studies have, however, considered differential propensities of observing the behaviors of different types of agents (information assortment). Furthermore, most previous studies have assumed that discriminators possess perfect information about others and incur no costs for gathering and storing this information. Here, we (1) consider both interaction assortment and information assortment, (2) assume discriminators have limited information about others, and (3) introduce a cost for information gathering and storage, in order to understand how the ability of discriminators to stabilize cooperation is affected by these steps toward increased realism. We report the following findings. First, cooperation can persist when agents preferentially interact with agents of other types or when discriminators preferentially observe other discriminators, even when they have limited information. Second, contrary to intuition, increasing the amount of information available to discriminators can exacerbate defection. Third, introducing costs of gathering and storing information makes it more difficult for discriminators to stabilize cooperation. Our study is one of only a few studies to date that show how negative interaction assortment can promote cooperation and broadens the set of circumstances in which it is know that cooperation can be maintained.

  • 131.
    Bryson, Joanna J.
    et al.
    University of Bath.
    Theodorou, Andreas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. University of Bath, Bath, UK.
    How society can maintain human-centric artificial intelligence2019Inngår i: Human-centered digitalization and services / [ed] Marja Toivonen and Eveliina Saari, Springer, 2019, s. 305-323Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Although not a goal universally held, maintaining human-centric artificial intelligence is necessary for society's long-term stability. Fortunately, the legal and technological problems of maintaining control are actually fairly well understood and amenable to engineering. The real problem is establishing the social and political will for assigning and maintaining accountability for artifacts when these artifacts are generated or used. In this chapter we review the necessity and tractability of maintaining human control and the mechanisms by which such control can be achieved. What makes the problem both most interesting and most threatening is that achieving consensus around any human-centered approach requires at least some measure of agreement on broad existential concerns.

    Fulltekst tilgjengelig fra 2021-06-04 11:17
  • 132.
    Brännström, Andreas
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi.
    Knowledge Elicitation of Human Activities Using a Graphical Modeling Language2018Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Recent, and ongoing, research has been addressing the general problem of representing complex human activities for the purpose to provide intelligent software agents with a way to identify, reason, and evaluate human activities. Reliable evaluation of complex human activities requires the intelligent agent to obtain a representation that comprises distinguishing features of an activity. This is a challenging task, since a person´s activity is driven by goals, motives, and norms that may be conflicting in a situation. In order to provide knowledge about human activities to an intelligent software agent, we require tools that can allow us modeling human activities enabling knowledge elicitation. This study has evaluated a software prototype of a graphical modeling language with the overall research question to find the minimum language elements required to elicit the knowledge of activities from a domain expert. Eight participants tested the prototype through think aloud usability sessions were their understanding of the structure of the language was tested. Qualitative data analysis was conducted using a Grounded theory approach, which validity has been discussed. The findings indicated that characteristics of the hierarchical structure of Activity Theory are a supportive theoretical framework for the graphical language that resembles the way occupational therapists reason when analyzing human activities. The study proposes a set of minimum elements for the graphical language. A focus a for future study is to target the intelligent software system to further expand and tune the language by the systems requirements.

  • 133.
    Brännström, Tomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    JavaScript and Web Integration of AgX Multiphysics Engine2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    JavaScript is the de facto language for client-side scripting on the web and has in recent years received a great boost in performance thanks to the `browser wars' where the different browser vendors compete to get higher market shares. AgX is a physics engine developed by Algoryx in Umeå, intended for use in simulations. This thesis explores possible methods of integrating JavaScript with AgX and in extension the possibility of integrating AgX into the web browser as a plugin, effectively enabling AgX for use in different web applications. Efforts were made to combine the embedded JavaScript API with the AgX browser plugin. This was found to be unfeasible for different reasons, although the AgX plugin as a separate piece of software was shown to work well.

  • 134.
    Buckland, Philip I.
    et al.
    Umeå universitet, Humanistiska fakulteten, Institutionen för idé- och samhällsstudier, Miljöarkeologiska laboratoriet.
    Eriksson, Erik J.
    Umeå universitet, Humanistiska fakulteten, Institutionen för idé- och samhällsstudier, Miljöarkeologiska laboratoriet.
    Palm, Fredrik
    Umeå universitet, Humanistiska fakulteten, Humlab.
    SEAD - The Strategic Environmental Archaeology Database: Progress Report Spring 20142014Rapport (Annet vitenskapelig)
    Abstract [en]

    This report provides an overview of the progress and results of the VR:KFI infrastructure projects 2007-7494 and (825-)2010-5976. It should be considered as a status report in an on-going long-term research infrastructure development project.

  • 135.
    Buckland, Philip I.
    et al.
    Umeå universitet, Humanistiska fakulteten, Institutionen för idé- och samhällsstudier, Miljöarkeologiska laboratoriet.
    Eriksson, Erik
    Umeå universitet, Humanistiska fakulteten, Institutionen för idé- och samhällsstudier, Miljöarkeologiska laboratoriet.
    Linderholm, Johan
    Umeå universitet, Humanistiska fakulteten, Institutionen för idé- och samhällsstudier, Miljöarkeologiska laboratoriet.
    Viklund, Karin
    Umeå universitet, Humanistiska fakulteten, Institutionen för idé- och samhällsstudier, Miljöarkeologiska laboratoriet.
    Engelmark, Roger
    Umeå universitet, Humanistiska fakulteten, Institutionen för idé- och samhällsstudier, Miljöarkeologiska laboratoriet.
    Palm, Fredrik
    Umeå universitet, Humanistiska fakulteten, Humlab.
    Svensson, Patrik
    Umeå universitet, Humanistiska fakulteten, Humlab.
    Buckland, Paul
    Panagiotakopulu, Eva
    Institute of Geography, School of GeoSciences, University of Edinburgh, UK.
    Olofsson, Johan
    Uppsala Municipal Council, Uppsala, Sweden.
    Integrating human dimensions of Arctic palaeoenvironmental science: SEAD – the strategic environmental archaeology database2011Inngår i: Journal of Archaeological Science, ISSN 0305-4403, E-ISSN 1095-9238, Vol. 38, nr 2, s. 345-351Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Environmental change has a human dimension, and has had so for at least the last 10 000 years. The prehistoric impact of people on the Arctic landscape has occasionally left visible traces, such as house and field structures. More often than not, however, the only evidence available is at the microscopic or geochemical level, such as fossil insect and seed assemblages or changes in the physical and chemical properties of soils and sediments. These records are the subject of SEAD, a multidisciplinary database and software project currently underway at Umeå University, Sweden, which aims to create an online database and set of tools for investigating these traces, as part of an international research infrastructure for palaeoecology and environmental archaeology.

  • 136. Burman, Erik
    et al.
    Hansbo, Peter
    Larson, Mats G.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    A simple finite element method for elliptic bulk problems with embedded surfaces2019Inngår i: Computational Geosciences, ISSN 1420-0597, E-ISSN 1573-1499, Vol. 23, nr 1, s. 189-199Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, we develop a simple finite element method for simulation of embedded layers of high permeability in a matrix of lower permeability using a basic model of Darcy flow in embedded cracks. The cracks are allowed to cut through the mesh in arbitrary fashion and we take the flow in the crack into account by superposition. The fact that we use continuous elements leads to suboptimal convergence due to the loss of regularity across the crack. We therefore refine the mesh in the vicinity of the crack in order to recover optimal order convergence in terms of the global mesh parameter. The proper degree of refinement is determined based on an a priori error estimate and can thus be performed before the actual finite element computation is started. Numerical examples showing this effect and confirming the theoretical results are provided. The approach is easy to implement and beneficial for rapid assessment of the effect of crack orientation and may for example be used in an optimization loop.

  • 137. Burman, Erik
    et al.
    Hansbo, Peter
    Larson, Mats G.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Samvin, David
    A cut finite element method for elliptic bulk problems with embedded surfaces2019Inngår i: GEM - International Journal on Geomathematics, ISSN 1869-2672, E-ISSN 1869-2680, Vol. 10, nr 1, artikkel-id UNSP 10Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We propose an unfitted finite element method for flow in fractured porous media. The coupling across the fracture uses a Nitsche type mortaring, allowing for an accurate representation of the jump in the normal component of the gradient of the discrete solution across the fracture. The flow field in the fracture is modelled simultaneously, using the average of traces of the bulk variables on the fractures. In particular the Laplace-Beltrami operator for the transport in the fracture is included using the average of the projection on the tangential plane of the fracture of the trace of the bulk gradient. Optimal order error estimates are proven under suitable regularity assumptions on the domain geometry. The extension to the case of bifurcating fractures is discussed. Finally the theory is illustrated by a series of numerical examples.

  • 138.
    Burström, Markus
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Zingmark, Mikael
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    How to provide a user friendly search interface based upon a libraries Open Public Access Catalogue2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Today many libraries offer their services via Internet and reach billions of visitors in different ages. The problem is that most of these library web sites are not customized for the users and they don’t deliver a good user experience. In this thesis we have studied both the interface and the users of an Open Public Access Catalog called CS Library. We found out how the users use the current system and how they want to use it. To achieve this we gathered data with different user studies at the Ume°a city library. A new interface was developed from the outcome of our user study. We created a set of guidelines that were followed when a new user customized design was developed for CS Library. The new design offers a better user experience and is customized by the users needs, desires and thoughts. The new design has been implemented as an interactive prototype with HTML, CSS, Javascript and Actionscript to convey a better feeling of the interface.

  • 139.
    Byrne, James
    et al.
    Dublin City University, Ireland.
    Svorobej, Sergej
    Dublin City University, Ireland.
    Giannoutakis, Konstantinos M.
    Centre for Research and Technology Hellas, Greece.
    Tzovaras, Dimitrios
    Centre for Research and Technology Hellas, Greece.
    Byrne, P. J.
    Dublin City University, Ireland.
    Östberg, Per-Olov
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N).
    Gourinovitch, Anna
    Dublin City University, Ireland.
    Lynn, Theo
    Dublin City University, Ireland.
    A review of cloud computing simulation platforms and related environments2017Inngår i: Proceedings of the 7th International Conference on Cloud Computing and Services Science: Volume 1: CLOSER, 2017, Vol. 1, s. 679-691Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Recent years have seen an increasing trend towards the development of Discrete Event Simulation (DES) platforms to support cloud computing related decision making and research. The complexity of cloud environments is increasing with scale and heterogeneity posing a challenge for the efficient management of cloud applications and data centre resources. The increasing ubiquity of social media, mobile and cloud computing combined with the Internet of Things and emerging paradigms such as Edge and Fog Computing is exacerbating this complexity. Given the scale, complexity and commercial sensitivity of hyperscale computing environments, the opportunity for experimentation is limited and requires substantial investment of resources both in terms of time and effort. DES provides a low risk technique for providing decision support for complex hyperscale computing scenarios. In recent years, there has been a significant increase in the development and extension of tools to support DES for cloud computing resulting in a wide range of tools which vary in terms of their utility and features. Through a review and analysis of available literature, this paper provides an overview and multi-level feature analysis of 33 DES tools for cloud computing environments. This review updates and extends existing reviews to include not only autonomous simulation platforms, but also on plugins and extensions for specific cloud computing use cases. This review identifies the emergence of CloudSim as a de facto base platform for simulation research and shows a lack of tool support for distributed execution (parallel execution on distributed memory systems).

  • 140.
    Bäckman, Nils
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Collision Detection of TriangleMeshes using GPU2011Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Collision detection in physics engines often use primitives such as spheres and boxes since collisions between these objects are straightforward to compute. More complicated objects can then be modeled using compounds of these simpler primitives. However, in the pursuit of making it easier to construct and simulate complicated objects, triangle meshes are a good alternative since it is usually the format used by modeling tools. This thesis demonstrates how triangle meshes can be used directly as collision objects within a physics engine. The collision detection is done using triangle mesh models with tests accelerated using a tree-based bounding volume hierarchy structure. OpenCL is a new open industry framework for writing programs on heterogeneous platforms, including highly parallel platforms such as Graphics Processing Units(GPUs). Through the use of OpenCL, parallelization of triangle mesh collision detection is implemented for the GPU, then evaluated and compared to the CPU implementation

  • 141. Börstler, Jurgen
    et al.
    Caspersen, Michael E.
    Nordström, Marie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Beauty and the Beast: on the readability of object-oriented example programs2016Inngår i: Software quality journal, ISSN 0963-9314, E-ISSN 1573-1367, Vol. 24, nr 2, s. 231-246Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Some solutions to a programming problem are more elegant or more simple than others and thus more understandable for students. We review desirable properties of example programs from a cognitive and a measurement point of view. Certain cognitive aspects of example programs are captured by common software measures, but they are not sufficient to capture a key aspect of understandability: readability. We propose and discuss a simple readability measure for software, SRES, and apply it to object-oriented textbook examples. Our results show that readability measures correlate well with human perceptions of quality. Compared with other readability measures, SRES is less sensitive to commenting and whitespace. These results also have implications for software maintainability measures.

  • 142.
    Börstler, Jurgen
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Nordström, Marie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Paterson, James H
    Glasgow Caledonian University, Scotland, UK.
    On the quality of examples in introductory Java textbooksInngår i: Transactions on Computing EducationArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Example programs play an important role in the teaching and learning of programming. Students as well as teachers rank examples as the most important resources for learning to program. Ex- ample programs work as role models and must therefore always be consistent with the principles and rules we are teaching.

    However, it is difficult to find or develop examples that are fully faithful to all principles and guidelines of the object-oriented paradigm and also follow general pedagogical principles and practices. Unless students are able to engage with good examples, they will not be able to tell desirable from undesirable properties in their own and others’ programs.

    In this paper we report on a study in which experienced educators evaluated the quality of object-oriented example programs for novices from popular Java textbooks. The evaluation was accomplished using an on-line checklist that elicited responses on the technical, object-oriented, and didactic quality of examples.

    In total 25 reviewers contributed 215 reviews to our data set, based on 38 example programs from 13 common introductory programming textbooks. Results show that the evaluation instru- ment is reliable in terms of inter-rater agreement. Overall, example quality was not as good as one might expect from common textbooks, in particular regarding certain object-oriented properties.

    We conclude that educators should be careful when taking examples straight out of a textbook.

  • 143.
    Börstler, Jürgen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Tenth workshop on pedagogies and tools for the teaching and learning of object-oriented concepts2007Inngår i: Object-oriented technology: ECOOP 2006 workshop reader / [ed] Mario Südholt & Charles Consel, Berlin: Springer Berlin/Heidelberg, 2007, s. 147-157Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    This report summarizes the results of the tenth workshop on pedagogies and tools for the teaching and learning of object-oriented concepts. The focus of this year’s workshop was on examples, modelling and abstraction. Participants agreed that carefully developed scaffolded examples are a key element for learning to program. For the teaching of modelling and abstraction this area, however, seems badly neglected. The workshop gathered 12 participants, all from academia, from 10 different countries.

  • 144.
    Börstler, Jürgen
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Bay, Omer Faruk
    Baturay, Meltem
    Trapp, Sonja
    Heintz, Matthias
    Weber, Sebastian
    embed4Auto-A PLE for Software Modelling2010Inngår i: ITICSE 2010: proceedings of the 2010 ACM SIGCSE annual conference on innovation and technology in computer science education, Association for Computing Machinery (ACM), 2010, s. 322-322Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We have developed courseware for UML/SysML modelling based on the needs of the European embedded/automotive industry. The courseware supports interactive modelling exercises. First evaluations show promising results.

  • 145.
    Börstler, Jürgen
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Dranidis, Dimitris
    Ramollari, Ervin
    Trapp, Sonja
    Heintz, Matthias
    Weber, Sebastian
    Sharing and discussing UML modeling exercises in a PLE2010Inngår i: ITICSE 2010: proceedings of the 2010 ACM annual conference on innovation and technology in computer science education, Association for Computing Machinery (ACM), 2010, s. 301-301Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present courseware for UML/SysML modelling that supports collaborative learning at a distance. Learners can solve interactive modelling exercises and discuss their solutions. First evaluations show promising results.

  • 146.
    Börstler, Jürgen
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Hadar, Irit
    Eleventh workshop on pedagogies and tools for the teaching and learning of object-oriented concepts2008Inngår i: Object-oriented technology. ECOOP 2007 workshop reader: ECOOP 2007 workshops, Berlin, Germany, July 30-31, 2007, final reports / [ed] Michael Cebulla, Berlin: Springer , 2008, s. 182-192Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    This report summarizes the results of the eleventh workshop on pedagogies and tools for the teaching and learning of object-oriented concepts. The focus of this year's workshop was on desirable properties of examples and the usage of simple tools. The workshop gathered 17 participants, all from academia, from 7 different countries.

  • 147.
    Börstler, Jürgen
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Hall, Mark S
    University of Wisconsin.
    Nordström, Marie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Paterson, James H
    Glasgow Caledonian University.
    Sanders, Kate
    Rhode Island College.
    Schulte, Carsten
    Freie Universität Berlin.
    Thomas, Lynda
    Aberystwyth University.
    An evaluation of object oriented example programs in introductory programming textbooks2009Inngår i: SIGCSE Bulletin inroads, ISSN 0097-8418, Vol. 41, nr 4, s. 126-143Artikkel i tidsskrift (Fagfellevurdert)
  • 148.
    Cabral, Regis
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    QoE: Quality of Experience: a conceptual essay2007Inngår i: Integration and Innovation Orient to E-Society, Vol 2: Seventh IFIP International Conference on e-Business, e-Services, and e-Society (13E2007), October 10–12, Wuhan, China / [ed] Weijun Wang, Yanhui Li, Zhao Duan et al, New York: Springer-Verlag New York, 2007, Vol. 252, s. 193-199Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The ICT industry and services are on the verge of substituting quality of service and utility functions; with quality of experience, QoE. While intuitive, QoE, has eluded the research community. QoE takes into account what the user is experiencing with new products and services. Once this information is collected, it becomes an input in the development of the new product or new service. But how does one measure directly quality of experience? In this conceptual paper, I discuss from an ICT perspective, the utility function and quality of service, QoS. I also present how active interested the industry is in QoE. I concluded with some key points that may serve as a guideline in the process of constructing the QoE function.

  • 149. Caianiello, Eduardo R.
    et al.
    Eklund, Patrik
    Department of Computer Science, Åbo Akademi, Åbo, Finland.
    Squillante, M.
    Ventre, A.G.S.
    Formalism and Implementations of C-calculus1989Inngår i: Computational Intelligence, I: Proceedings of the International Conference, Milan Italy, 26-30 Sept., 1988 / [ed] Alberto Martelli and Giorgi Valle, Amsterdam: Elsevier, 1989, s. 15-26Konferansepaper (Fagfellevurdert)
  • 150.
    Campano, Erik
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi.
    Artificially Intelligent Black Boxes in Emergency Medicine: An Ethical Analysis2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Det blir allt vanligare att föreslå att icke-transparant artificiell intelligens, s.k. black boxes, används inom akutmedicinen. I denna uppsats används etisk analys för att härleda sju riktlinjer för utveckling och användning av black boxes i akutmedicin. Analysen är grundad på sju variationer av ett tankeexperiment som involverar en läkare, en black box och en patient med bröstsmärta på en akutavdelning. Grundläggande begrepp, inklusive artificiell intelligens, black boxes, metoder för transparens, akutmedicin och etisk analys behandlas detaljerat. Tre viktiga områden av etisk vikt identifieras: samtycke; kultur, agentskap och privatliv; och skyldigheter. Dessa områden ger upphov till de sju variationerna. För varje variation urskiljs en viktig etisk fråga som identifieras och analyseras. En riktlinje formuleras och dess etiska rimlighet testas utifrån konsekventialistiska och deontologiska metoder. Tillämpningen av riktlinjerna på medicin i allmänhet, och angelägenheten av fortsatt etiska analys av black boxes och artificiell intelligens inom akutmedicin klargörs.

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