HotelCategoryWebPrices in CHFRemarks
Hotel Bern

Best Western
4 Star

Websitearound 170.00 for a single room
around 210.00 for a double room
We have a special corporate rate
Hotel GlockeBackpackersWebsite

around 76.00 for a single room
around 144.00 for a double room
bed in dormitory from 37.00

Mostly dormitories, some double and single rooms
Ibis BudgetAccor Hotels Budget HotelWebsitearound 100.00 for a single or a double roomOutside town, about 15 mins. by bus to the railway station
Landhaus BernBackpackersWebsitearound 95.00 for a single room
around 120.00 for a double room
bed in dormitory from 38.00
prices include breakfast

Peter Mayr

University of Colorado Boulder, USA

Zauberwürfel, Sudoku und Algebra

Lösen Sie gern Sodoku oder Zauberwürfel? Dabei hilft einem die Schulmathematik fürs erste nicht weiter. Trotzdem führen diese Spiele zu einer Reihe interessanter mathematischer Probleme, mit denen sich sogar die aktuelle Forschung beschäftigt:

  • Wieviele Drehungen braucht es, damit man sicher jede Konfiguration des Zauberwürfels auflösen kann?
  • Wieviele verschiedene Sudokus gibt es?
  • Wie kann man Sudokus erstellen?
  • Sind Sudokus oder Würfel leichter zu lösen?

Die letzte Frage führt zum wahrscheinlich berühmtesten offenen Problem der Informatik: Ist P gleich NP? Das heisst, kann jedes Problem, für das eine Lösung schnell überprüft werden kann, auch schnell gelöst werden? Peter Mayr zeigt, wie Algebra beim Spielen und beim Unterscheiden zwischen leichten und schweren Problemen hilft.

Baris Sertkaya

Frankfurt University of Applied Sciences, Germany

Linked Data meets Formal Concept Analysis

Linked Data is a set of best practices for publishing and connecting structured data on the Web. It is one of the major building blocks of Semantic Web, the machine understandable extension of the existing Web.The idea of linking data on the Web has already been adopted by several data providers, giving rise to a global data space consisting of billions of interlinked data records. In this talk, we present the concept and the underlying technology of linked data like the RDF format and the SPARQL query language. Moreover, we discuss how Formal Concept Analysis can help to improve the quality of linked data.

Jens Zumbrägel

TU Dresden, Germany

Kryptologie: Wie sicher sind online Transaktionen?

Emails und online Transaktionen gehören zu unserem Alltag. Habe ich die Gewissheit, dass nur mein Gesprächspartner, die an ihm addressierte Emails liesst? Die Sicherheit von online Transaktionen basiert auf modernen Public-Key-Verschlüsselungsverfahren, die meist auf Zahlentheorie fussen. Dort spielt das diskrete Logarithmusproblem (DLP) eine wesentliche Rolle. Seit 2014 hat Herr Zumbrägel zusammen mit zwei Kollegen den DLP-Record inne. An neueren Arbeiten konnten die aufzeigen, dass für bestimmte Charakteristik das DLP wesentlich geringere Komplexität hat als bisher angenommen. Welche Wirkung hat dies auf die Sicherheit von online Transaktionen? Jens Zumbrägel schaut mit Ihnen die aktuelle Lage an.

Geoff Ostrin

Bern University of Applied Sciences, Switzerland

Constraint Satisfaction Problems: From the classroom, for the classroom

There is a certain serendipity when we discover that what we teach in the classroom can actually be applied in the real world. At the Berner Fachhochschule we offer a course titled Management Science where we teach the use of linear programming in solving constraint satisfaction problems (CSP). This knowledge and associated methods are just what we need to solve many practical problems in the running and organisation of universities and schools. From the first day at school, where we need to determine how pupils should be collected together in classes; through the following years, where we need to find the best mix of courses that best match what the pupils desire; all the way to the final organisation of the week of oral exams; each step can be modelled as a CSP and solved appropriately. In my talk I will demonstrate the general type of practical problem that we can solve and discuss some of the interesting issues that have arisen in constructing models for finding appropriate solutions.

Jens Zumbrägel

TU Dresden, Germany

Simple Semirings and Post-Quantum Cryptography

Virtually all of today's public-key cryptosystems are based either on the integer factorisation problem or the discrete logarithm problem. However, Shor's algorithm renders all of them completely broken once a quantum computer is built, so the search for alternatives is a very active ongoing research area.

The quantum attack on the discrete logarithm problem makes substantial use of the cyclic group structure, so that generalising the viewpoint by considering semigroup actions makes sense. A promising candidate for a cryptographically interesting semigroup action is based on matrices over simple semirings. These are semirings that do not allow for smaller homomorphic images so that a Pohlig-Hellman-type attack is avoided. Recent results on the classification of finite simple semirings (in terms of residuated maps in lattices) provide a wealth of effective examples. Further research is required to assess the security of the resulting cryptosystems.

Laura Ciobanu

Heriot Watt University Edinburgh, UK

Solving equations in free groups

Solving equations in free groups and semigroups has important connections to algebra, geometry and unification theory, and was shown to be decidable by Makanin in the 1980's. Since Makanin's algorithm is extremely complex, there have been efforts to simplify and modify it for the last 30 years.

In this talk I will describe work with Murray Elder and Volker Diekert on finding all solutions to an equation in a free group in an efficient way. We prove that the set of all solutions to an equation of length n can be encoded in a finite graph, where solutions can be simply read-off the graph, and the graph can be constructed in NSPACE(n log n).

David M. Clark

State University of New York, New Paltz, USA

Evolution of Terms for Groupoid Operations

Theorems of Rosenberg and Rousseau make it easy to determine if a finite groupoid is primal. But finding a term to represent an operation on a primal groupoid is computationally unfeasible by standard methods. This talk will present an efficient evolutionary algorithm to do this. Two theorems explain the success of this algorithm, one based on the assumption that the groupoid is idemprimal and the other based on the assumption that its term to term operation function is continuous. A third theorem gives a condition for term continuity using two efficiently testable properties that appear to hold for almost all finite groupoids. This algorithm has potential application to circuit design and to cryptography.

Michael Pinsker

TU Wien, Austria / Charles University Prague, Czech Republic

Equations in oligomorphic algebras

When the term clone of a finite algebra satisfies non-trivial equations (i.e., equations not satisfiable by projections), then this has numerous interesting consequences for the structure of the algebra, some of which are quite recent discoveries. Even more recently, analogous consequences of non-trivial equations have been shown for oligomorphic algebras, i.e., algebras on a countably infinite domain whose term clone contains a sufficiently large permutation group. In particular, surprising links between equations in algebras and model-theoretic concepts have appeared. We survey these results and their applications to constraint satisfaction problems in theoretical computer science.

Heinz-Peter Gumm

Universität Marburg, Germany

Varieties of coalgebraic signatures

A signature F is a Set-Endofunctor. While algebraic signatures correspond to polynomial functors, and thereby are rather plain objects, coalgebraic signatures, in order to model all kinds of state based systems, must exhaust the full spectrum of Set-Endofunctors.

Preservation properties of such signature functors have a vital influence on their co-algebraic theories. Among those properties studied are: weak preservation of pullbacks, of kernel pairs or of preimages. We add to this weak preservation of constant maps, i.e. that Fc is a constant map whenever c was. Inspired by an observation in a paper by Dent, Kearnes and Szendrei, we prove that every connected monadic functor weakly preserves the pullback of constant maps.

We briefly investigate such conditions for functors arising as free-algebra functors FV(X) where V is a variety of universal algebras. If V is a Malcev variety then FV(X) weakly preserves pullbacks. Conversely, if V is n-permutable and FV weakly preserves pullbacks, then V must be Malcev.

Jürg Schmid

University of Bern, Switzerland

Commutative Information Algebras

Algebraic structures of a kind similar to these we will discuss in this talk surfaced first in [1]. The basic idea is to formulate laws governing the behaviour of abstract pieces of information. This results in two-sorted algebras (Φ, E) where Φ is a commutative idempotent semigroup (modeling the "pieces of information") and E a collection of maps  εq : Φ→Φ, associated to a set Q of questions in such a way that for φ ∈ Φ  and q ∈ Q, εq (φ) is the information contained in φ  which is relevant to the question q.

The purpose of the talk is NOT to justify the usefulness of these algebras for Theoretical Computer Science by exhibiting many examples and applications there (they exist, see e.g. [2]), but rather to examine them from the point of view of (Universal) Algebra, especially with to goal of finding uniform representations of such algebras by rather simple set theoretical constructs over a basic universe. In order to make these lofty statements somewhat precise, we remark that Cignoli's Q-distributive lattices [3] (and Halmos' Monadic algebras) are special cases of commutative information algebras.

[1] Shenoy, P., and Shafer, G. Axioms for Probability and Belief-Function Propagation, in Machine Intelligence and Pattern Recognition, Vol. 9 (1990), 169 - 198
[2] Kohlas, J., Information Algebras: Generic Structures for Inference Series: Discrete Mathematics and Theoretical Computer Science, Springer 2003
[3] Cignoli, R., Quantifiers on distributive lattices, Discrete Mathematics 96, 183 - 197

Marcel Tonga

University of Yaounde I, Cameroon

On residuated lattices and fuzzy algebraic structures

We first have a look at some subclasses of residuated lattices that are not MTL-algebras; then we give some examples of fuzzy algebraic structures, with focus on fuzzy filters of lattices and fuzzy ideals of rings. The lattice of fuzzy ideals of a ring supports a structure of residuated lattice.