Simultaneous deformations of algebras and morphisms via derived brackets

We present a method to construct explicitly L-infinity algebras governing simultaneous deformations of various kinds of algebraic structures and of their morphisms. It is an alternative to the heavy use of the operad machinery of the existing approaches. Our method relies on Voronov's derived bracket construction.Comment: 20 pages. Final version, accepted for publication, and significantly shorter than version v1. Our previous submission arXiv:1202.2896v1 has been divided into two parts. The present paper contains the algebraic applications of the theory, while the geometric applications are the subject of the paper arXiv:1202.2896v2 ("Simultaneous deformations and Poisson geometry"

Comparison between a FEL amplifier and oscillator

Previous experiments with the Raman FEL, situated at the Twente University, showed that the output was influenced by the rather strong increase of the current density with time. The field emission diode has been modified to produce a more constant current pulse to simplify the analysis of the measurements. This resulted in a lower current density of the electron beam. With this new diode two set-ups are studied. In the first set-up the laser is still configured as an amplifier whereas in the second set-up the laser configuration is changed into an oscillator using a Bragg reflector with a space-variable corrugation height. For both set-ups we measured the frequency spectrum for specific values of undulator and guide magnetic fields. The relative performance of the amplifier and the oscillator configuration will be presented

Neighbourhood Abstraction in GROOVE - Tool Paper

In this paper we discuss the implementation of neighbourhood graph abstraction in the GROOVE tool set. Important classes of graph grammars may have unbounded state spaces and therefore cannot be verified with traditional model checking techniques. One way to address this problem is to perform graph abstraction, which allows us to generate a finite abstract state space that over-approximates the original one. In previous work we presented the theory of neighbourhood abstraction. In this paper, we present the implementation of this theory in GROOVE and illustrate its applicability with a case study that models a single-linked list

Graph Subsumption in Abstract State Space Exploration

In this paper we present the extension of an existing method for abstract graph-based state space exploration, called neighbourhood abstraction, with a reduction technique based on subsumption. Basically, one abstract state subsumes another when it covers more concrete states; in such a case, the subsumed state need not be included in the state space, thus giving a reduction. We explain the theory and especially also report on a number of experiments, which show that subsumption indeed drastically reduces both the state space and the resources (time and memory) needed to compute it.Comment: In Proceedings GRAPHITE 2012, arXiv:1210.611

Using Graph Transformations and Graph Abstractions for Software Verification

In this paper we describe our intended approach for the verification of software written in imperative programming languages. We base our approach on model checking of graph transition systems, where each state is a graph and the transitions are specified by graph transformation rules. We believe that graph transformation is a very suitable technique to model the execution semantics of languages with dynamic memory allocation. Furthermore, such representation allows us to investigate the use of graph abstractions, which can mitigate the combinatorial explosion inherent to model checking. In addition to presenting our planned approach, we reason about its feasibility, and, by providing a brief comparison to other existing methods, we highlight the benefits and drawbacks that are expected