Department seminar 2007
Please contact Øyvind Ytrehus, Dag Haugland or Michal Walicki if you have suggestions for seminar speakers.
Seminars are held Thursdays at 14:15 in the large auditorium (2144),
2nd floor, Høyteknologisenteret, Datablokken.
Refreshments after the seminar
in the GREEN ROOM (room 4151 on the 4th floor).
Fall 2007
- September 6
-
Professor Brian S Hoyle, University of Leeds, UK
Title: Spatially Critical Sensor and Actuation Networks.
Abstract: Sensor and actuation networks offer a generic platform from which a wide range of applications can be realised in many fields. Many candidate applications have a spatially critical aspect, from environmental monitoring and control to security and surveillance. Communication networks have enabled many distributed applications, and have exploited a wide range of network topologies and technologies.
The presentation reviews the needs of spatially critical applications and proposes new methodologies that aim to exploit wired and wireless sensor and actuation networks to deliver efficient implementations. It contrasts a classical centralized network solution in which spatially critical data will typically be offloaded for analysis; with a smart network solution, which features inter-node cooperation pivoting upon location, and is able to track specified application properties dynamically. A number of examples are discussed.
Speaker: Brian Hoyle is Professor of Vision and Systems and currently a member of the School of Process, Environmental and Materials Engineering. His research interests are based upon systems engineering and specifically in distributed sensing systems and networks and process sensing including process tomography. He is also Director for Enterprise and Knowledge Transfer, Faculty of Engineering University of Leeds, Leeds, UK.
- Monday October 1 14:15 in the large auditorium (2144)
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Erik Boman, Sandia National Laboratories in Albuquerque, New Mexico, USA.
Title: Combinatorial Scientific Computing: Enabling Petascale Simulations for Science
Abstract: Computer simulation is an increasingly important tool in research and science. Combinatorial scientific computing is the use of combinatorial and discrete techniques to enable large-scale scientific computing. We first give an overview of research activities in the CSCAPES institute (supported by the US DOE), including load-balancing, automatic differentiation, graph coloring, and sparse matrix ordering. Then we present a more detailed account of partitioning and load-balancing algorithms for parallel scientific computing.
- October 4
-
Thomas Ågotnes, Høgskolen i Bergen
Title: Aggregation and Paradoxes.
Abstract: The Department of Informatics has appointed a committee for evaluating a single applicant for a new professorship. The committee members all make up their minds about the following propositions: (i) the applicant should be given an offer if she is qualified, (ii) the applicant is qualified, and (iii) the applicant should be given an offer. There are three committee members, and their view on the questions (i)/(ii)/(iii) are as follows. Member A: yes/yes/yes; member B: yes/no/no; member C: no/yes/no. Since they disagree, they decide to settle the issue by majority voting on each of (i), (ii) and (iii). What do the committee decide? The problem of aggregating information from different sources comes up when we need to combine information from several databases; when you and you spouse need to agree on a new car (preference aggregation); when the beliefs of two experts must be combined; when a group of agents must coordinate to perform a joint action; in e-government mechanisms (preference aggregation again). Yet the aggregation problem, of which the special case of preference aggregation has been studied extensively in social choice theory, is plagued by dilemmas, paradoxes and impossibility results. I will talk about some of these, and about why computer scientists should be concerned.
- October 11
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Dr. Samuel Subbey, Institute of Marine Research, Bergen, Norway.
Title: Are classical solutions to inverse and ill-posed problems growing long in the tooth?
Abstract: Starting with data and a general principle or model, inverse theory addresses the problem of estimating the solution set of model parameters. Usually, for a given data set, the solution set is non-unique, and the problem is referred to as being ill-posed.
Classical solutions to inverse and ill-posed problems regularization, i.e., solving a stable variant of the originally unstable problem.
The aim of this talk is to discuss the classical approach to solving inverse and ill-posed problems when the data and model are known with modest accuracy. Simple examples will be presented to highlight key points.
Keywords: Inverse, ill-posed, matrix equation, integral equation, optimization, regularization, parameterization, spline functions
- October 18
-
Markus Roggenbach, Swansea University, UK
Title: CSP - new insights into an old paradigm
Abstract: The process algebra CSP is a well established formalism to model and reason about concurrent systems such as credit card terminals or flight booking systems. We report on how CSP has been used in industrial applications such as the software development of the international space station (ISS) and show how our tool CSP-Prover can be of help in such scenarios. This practice has lead to the question if the calculus implemented CSP-Prover is complete - for which we found a positive answer in case of one specific CSP model. This is joint work with Y. Isobe (AIST, Japan).
- October 25
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Marco Baldi, Universita Politecnica delle Marche, Ancona, Italy
Title: McEliece cryptosystem based on LDPC codes
Abstract: The McEliece cryptosystem, proposed in 1978, is a public-key cryptosystem based on algebraic coding theory that revealed to be very secure. The original McEliece cryptosystem is still unbroken, in the sense that no algorithm able to realize a total break in an acceptable time has been presented up to now. In spite of this, however, few attention has been devoted to it with respect to other solutions, for two main reasons: i) the large size of its public key and ii) its low transmission rate (that is about 0.5). LDPC codes seem natural candidates to overcome such drawbacks, because of their sparse parity-check matrices, that could form the public keys, and the flexibility in transmission rates. Such advantages, however, must combine with the need for security. The seminar discusses a previous LDPC-based instance of the McEliece cryptosystem and illustrates its cryptanalysis. Many attacks are presented, that prevent from using some families of LDPC codes and, eventually, a "killer" attack is identified, able to produce a total break of the cryptosystem. However, a new instance of the system is described that is immune to all the considered attacks and can achieve the prefixed objectives with limited complexity. ------------------------------------------------------------------------------------------------------------------------ As concerns its contents, a useful reference would be the long paper in which we have collected all our most important results, and that we have recently submitted to the IEEE IT Transactions. A preprint of that work is available at: http://arxiv.org/abs/0710.0142
- November 1
-
Jan Heering, CWI, Amsterdam
Title: Developments in Domain-Specific Languages
Abstract: Domain-specific languages (DSLs) are languages tailored to a specific application domain. They offer substantial gains in expressiveness and ease of use compared with general-purpose languages in their domain of application. Although the use of DSLs is by no means new, it is receiving increased attention in the context of model-driven engineering, development of parallel software for multicore processors, and ultra-large-scale systems. We discuss these trends from the perspective of the roles DSLs have traditionally played.
- November 8
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Rob Bisseling, Dept. of Mathematics, Utrecht University, The Netherlands
Title: Parallel PageRank Computation
Abstract: This talk will present the parallel computation of the Google PageRank of a set of web pages. In this application, a sparse matrix with nonzeros representing links between web pages is repeatedly multiplied by a vector. The data are partitioned using Mondriaan, a two-dimensional, multilevel, hypergraph-based partitioning package.
Brief biography: Rob Bisseling is an associate professor in computational science at the Mathematics Department of Utrecht University, the Netherlands. His main research field is parallel computing and his current research interests are sparse matrix computations, information retrieval, bioinformatics, and fast Fourier transforms. He is author of the book, "Parallel Scientific Computation: A Structured Approach using BSP and MPI", Oxford University Press, March 2004.
- November 15
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Lars Michael Kristensen Aarhus universitet
Title: Let's aim at going all the way - from Formal Specification and Verification to Implementation of Communication Protocols
Abstract: Communication protocols play a still more important role in our everyday use of information technology, and it is therefore of vital importance that they work as intended. Protocols are, however, challenging to design and implement. Important reasons for this are the inherent presence of concurrency and non-determinism which induces complex behaviour thereby making testing and debugging difficult. The use of formal modelling and state space exploration (model checking) is a main approach to model-based development and verification of protocols. The basic idea of state space exploration is to verify behavioural properties of protocols by exploring the reachable states and state changes of the protocol under consideration. Many projects have been carried out and reported in the literature on successful application of formal modelling and verification of Internet protocols. The formal models are, however, seldom used (directly) as a basis for implementation of the protocols. This talk presents our initial work conducted in the ASCoVeCo research project concerned with formal modelling, verification, and implementation of the Dynamic MANET On-demand Routing (DYMO). DYMO is a routing protocol currently being developed by the IETF MANET working group for multi-hop communication in mobile ad-hoc networks (MANETs). A formal model of the DYMO protocol has been developed using the Coloured Petri Nets (CPNs) modelling language and is being verified using state space exploration. As part of the project, we have developed ASAP which is an Eclipse-based computer tool for state space exploration of CPN models, and the Virtual Internetworking Environment (VIE) to be used as the initial target platform for the DYMO implementation.
- November 21-22
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We will have a "A Helleseth Symposium" with a lot of interesting talks and there will therefore be no ordinary seminar this week.
Program: To be announced.
- November 29
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Xue-Cheng Tai, Department of Mathematics, University of Bergen, Norway
Title: PDE methods for image processing and application to medical imaging
Abstract: In this talk, we will review the methods and applications that have been done by the image processing group at UIB.
First, we will introduce some of the models which has been tested on noise removal. Especially, some higher order nonlinear PDE filters are designed to avoid stair-casing and at the same time preserve edges. Afterwards, we will explain some of the new models which have been developed for image segmentation, surface and edge detection. The new level set ideas just need to use one level set function to identify arbitrary number of objects. It also avoids the reinitialization and the non-differentiable functions used in traditional level set methodology. Recently, this ideas have been combined with the four-color theorem for map-painting for segmentation of 2D fluorescence microscopy images images. In the end, we will explain some nonlinear PDEs for image inpainting. This idea is also used for noise removal.
- December 6
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Mikael Rönnqvist, Norwegian School of Economics and Business Administration, Bergen, Norway
Title: Cost sharing in collaborative forest transportation
Abstract: Transportation planning is an important part of the supply chain or wood flow chain in forestry. There are often several forest companies operating in the same region and collaboration between two or more companies is rare. However, there is an increasing interest in collaborative planning as the potential savings are large, often in the range 5-15%. There are several issues to agree on before such collaborative planning can be used in practice. One aspect is to use tailor-made optimization based decision support systems. A second aspect is how savings should be distributed among the participants. We study a number of possibilities based on economic models including Shapley value, the nucleolus, separable and non-separable costs, shadow prices and volume weights. We also propose a new allocation method, with the aim that the participants relative profits are as equal as possible. A large case study comprising eight forest companies in Sweden analyzed.
- December 13
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Douglas Rogers
Title: On Golden Plan?
Abstract: It has recently been suggested that the influence of golden section was at work in the ground plan of the Sidi Oqba Mosque, in Kairouan, Tunisia. The geometry inherent in such a plan is examined and found to have much in common with some well-known 'vanishing area' puzzles. However, such puzzles may themselves have arisen out of a geometrical misconception in an architecture handbook from 1545, while their association with the Fibonacci numbers may have originally been more a matter of happy accident than design.
Spring 2007
- January 25
-
Kjell Jørgen Hole
Title: Nettbanksikkerhet i perioden 2003-2006.
- February 1
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Douglas Rogers
Title: After Euler - permutations with and without cycles of prescribed length
- February 8
-
No seminar
- February 15
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Boris Lenhard, CBU
Title: Gene regulation and animal development: a bioinformatics approach
- February 22
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Dag Finne, BTO
Tema: Kommersialisering av forskningsresultat
- March 1
-
No seminar
The lecture room will be redecorated.
- March 8
-
Petter Ole Jakobsen, CTO (Teknologi direktør vizrt)
Steinar Søreide, Utviklingssjef Bergen
Vizrt, softwareutvikling, produkter og metoder.
- March 15
-
Min Chen
CANCELLED
- March 22
-
Fredrik Manne
Title: Self-stabilizing Algorithms
- March 30, Kl. 10-11 (Note time)
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Irina Naydenova
Title: Theory of Unequal Error Protection Codes
(førelesing med fritt valgt emne for PhD)
- April 5
-
NO SEMINAR (Easter vacation)
- April 12
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Trond Steihaug
Title: CPR and Beyond
- April 19
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Hamid R. Sadjadpour, University of California, Santa Cruz
Title: Many-to-many communications for ad hoc networks.
On Friday, April 20, 1015-1100, Professor Sadjadpour will give a follow up talk in the Selmer Center (meeting room 5th floor).
Title: Beyond Network Coding: Toward Scalable Ad Hoc Networks
- April 26
-
NB! In aud. 2142.
Dominique Aze, Univ. Paul Sabatier, Toulouse
Title: The Ekeland Variational Principle Revisited
- May 3
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Matthew Parker
Title: A New Take on Complementary Sequence Construction
- May 10
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Aslak Tveito, Simulasenteret
Title: Om Simulasenteret med eksempler fra forskningen
- May 17
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Ikkje seminar
- May 24
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Ikkje seminar
(Fagutvalet arrangerer bedriftsbesøk frå Google kl. 1400. Påmelding sjå her ) - May 31
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Jan Arne Telle, Inst. for informatikk, UiB
Title: Physical Mapping of DNA with some undetected overlaps: an efficient Parameterized Graph Algorithm.
Abstract: In 1994 Ron Shamir proposed the following simplified formulation of the physical mapping problem encountered in molecular biology. The DNA molecule is viewed as an interval on the real line from which we extract clones. The goal is to determine the placement of the clones as subintervals. By tests using probes we have already determined which pairs of clones overlap, although a few overlaps may have gone undetected. The problem is to insert the fewest number k of extra overlaps that will allow an ordering of the clones as subintervals of the real line. The data is modeled as a graph with one vertex per clone and an edge for each overlap, and the decision problem becomes
Input: (G,k) where G a graph and k an integer
Question: Can you add at most k edges to G to get an interval graph?
This problem is NP-complete. Shamir et al posed the question if it was FPT, i.e. if there existed a polynomial-time preprocessing algorithm that would transform any input (G,k) into an input (H,k') having the same yes/no answer and where the size of H was a function of k only. As usual, a solution to this decision problem can be used to solve the original problem. In this talk we present such an algorithm and in particular the bounded-search-tree technique that it uses. This technique is well-known in the field of Parameterized Algorithms that is gaining attention lately as offering practical ways to cope with NP-complete problems. - June 7
-
Jorge Cardoso, Universidade da Madeira, Portugal
Title: The Semantic Web
Short bio: Dr. Cardoso received his Ph.D. in Computer Science from the University of Georgia, USA. He was the co-organizer and co-chair of the First, Second, and Third International Workshop on Semantic and Dynamic Web Processes and is the editor of 3 books on semantic Web and Web services. He is on the Editorial Board of the Enterprise Information Systems Journal, the International Journal on Semantic Web and Information systems, and the International Journal of Information Technology.
Fall 2006
- August 31
-
Lene Favrholdt
Title: A new variant of on-line bin packing
Lene Favrhold is a new adjunct professor at our Institute. Her research interests are in on-line algorithms. - September 28
-
Gregory Gutin
Title: Worst Case Analysis of Greedy, Max-Regret and Other Heuristics for Multidimensional Assignment and Traveling Salesman Problems
Gregory Gutin is a professor at the Department of Computer Science, Royal Holloway, University of London. His research interests include graphs and combinatorics (theory, algorithms and applications), combinatorial optimization, and linear and integer programming. - October 5
-
Mohamed El Ghami
Title: New Primal-dual Interior-point Methods Based on Kernel Functions
Mohamed El Ghami is a new postdoc at the institute (optimization group). His main research interests are in interior-point methods.
- October 19
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Ivan Viola
Title: Introduction and My Contributions at IEEE Visualization
Ivan Viola is a new postdoc at the institute (visualization).
- October 26
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Kees Roos
Title: Introduction to conic optimization with applications
rof. C. Roos is a Professor at the Department of Computer Science, Optimization group, at Delf University of Technology, The Netherlands. His main research interests are Interior point methods. He has published more than 110 papers in international journals, and author and coauthor of 8 books. - November 9
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Douglas Rogers
Title: Golomb rulers, radio telescopes and other uses of difference triangles
- November 23
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Matthew Parker
Title: Lost in Hilbert Space?
- November 30
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Zinovy Diskin
Title: Model-Driven Engineering and Mathematics: A New Golden Age?
Zinovy Diskin Zinovy Diskin received PhD in math from the University of Latvia in 1994 and worked in industry and academia in Latvia and US. He has been dealing with models and modeling in different contexts: logic management in algebraic logic, view and schema integration in database design, metadata management in enterprise data integration. Currently he is working in an IBM-CITO-Queen's University funded project on formal semantics for UML (one of industrial standards for MDE).
Spring 2006
- January 26
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Randi Moe.
Title: Sudoku-strategier
Randi Moe is Dr.Scient from UiB and has worked as a researcher for Parallab. She is the reigning Norwegian champion of Sudoku
- February 2
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Lars Thomas Hansen.
Title: Issues and methods in software development at Opera Software
Lars Thomas Hansen received his PhD from Northeastern University in 2000 and has since then been working at Opera Software in Oslo
- February 9
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Rune Djurhuus
Title: Contextual insight - from searching to knowing
Rune Djurhuus has been working as a research scientist for Fast Search & Transfer in Oslo since 1999.
- February 16
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Angela Barbero
Title: Network Coding
Angela Barbero is a guest researcher at the Selmer Center. She is a professor at the Department of Applied Mathematics, University of Valladolid, Spain.
- March 2
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Sergey Kitaev
Title: Patterns and their generalizations
Sergey Kitaev received his PhD from Gøteborg University and is currently an Assistant Professor at Reykjavik University
- March 9
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David Wood
Title: Drawings of graphs in two and three dimensions
David Wood received his PhD from Monash Univ in Australia, before globetrotting on to postdoctoral positions at Charles Univ in Prague, McGill Univ in Toronto, and Univ P Catalunya in Barcelona, among others.
- March 23
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Knut Erstad
Title: Software development in Vizrt
Knut Erstad received the cand.scient. degree from our department in 2002, and is now working as a developer at Vizrt's main office in Bergen.
- April 20
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Erling Moxnes
Title: Stochastic optimisation in policy space: Method, program package, and two applications
Erling Moxnes is a professor in System Dynamics at the University of Bergen. His main interests are in natural resources management and complex systems pedagogics.
- April 24 - NB Monday at 14:15 (postponed from April 6)
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Kai Olsen
Title: Kan vi opprettholde kvaliteten i realfagstudiene?
Kai Olsen is Professor at Høgskolen i Molde, Prof II here, and an active participant in national debates on teaching and research. This seminar will be held in Norwegian.
- April 27
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Douglas Rogers
Title: On combinatorial precursors of Sudoku
Douglas Rogers is a combinatorial mathematician whose research collaborations span the globe, for several years including also Bergen.
- May 4
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Herman Ruge Jervell
Title: Trees and processes
Herman Ruge Jervell is Professor in the Department of Informatics at UiO. In an interview from 2004 he was called En matematikkens filosof
- May 11
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Peter Møller
Title: Bruk og organisering av IT regjeringskvartaler - En prosess for profesjonalisering og industrialisering
Peter Møller received his cand scient from this department in 1990 and is described by Computerworld as possessing today 'the most powerful position in Norwegian Information Technology'.
- June 15
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Virginia Torczon
Title: Generating Set Search for Linearly Constrained Optimization: Theory and Implementation
Virginia Torczon is Professor at the Department of Computer Science, College of William & Mary.
