Showing papers by "Grzegorz Rozenberg published in 2018"

Reaction Systems, Transition Systems, and Equivalences

Abstract: Reaction systems originated as a formal model for processes inspired by the functioning of the living cell. The underlying idea of this model is that the functioning of the living cell is determined by the interactions of biochemical reactions and these interactions are based on the mechanisms of facilitation and inhibition. Since their inception, reaction systems became a well-investigated novel model of computation. Following this line of research, in this paper we discuss a systematic framework for investigating a whole range of equivalence notions for reaction systems. Some of the equivalences are defined directly on reaction systems while some are defined through transition systems associated with reaction systems. In this way we establish a new bridge between reaction systems and transition systems. In order to define equivalences which capture various ways of interacting with an environment, we also introduce models of the environment which evolve in a finite-state fashion.

Graph Surfing by Reaction Systems

Abstract: In this paper, we introduce graph-based reaction systems as a generalization of set-based reaction systems, a novel and well-investigated model of interactive computation. Graph-based reaction systems allow us to introduce a novel methodology for graph transformation, which is not based on the traditional “cut, add, and paste” approach, but rather on moving within a “universe” graph B (surfing on B) from a subgraph of B to a subgraph of B, creating subgraph trajectories within B. We illustrate this approach by small case studies: simulating finite state automata, implementing a shortest paths algorithm, and simulating cellular automata.

Membrane Computing 18th International Conference, CMC 2017, Bradford, UK, July 25-28, 2017, Revised Selected Papers

Abstract: We aim to compare functionality of symport/antiport with embedded rewriting to that of symport/antiport accompanied by rewriting, by two-way simulation, in case of tissue P systems with parallel communication. A simulation in both directions with constant slowdown is

Linking Exploration Systems with Local Logicsover Information Systems.

Abstract: In the paper, we discuss an extension of exploration systems introduced by Andrzej Ehrenfeucht and Grzegorz Rozenberg. The extension is defined by adding an interpretation of nodes and edges in zoom structure of exploration system. The interpretation is based on the concepts, namely local logic and logic infomorphism, from the notion of information flow by Jon Barwise and Jerry Seligman. This extension makes it possible, in particular, to give a natural interpretation of reaction systems in exploration systems as tools for controlling attention in reasoning about the perceived situation in the physical world.

Computational aspects of tomographic and neuroscientific problems

Abstract: The human brain can be described as a complex network, formed by spatially distributed, but functionally linked regions that continuously share information with each other. This arrangement ensures efficiency and resilience to damage. In this view, the characterization of brain connectivity is necessary to increase our understanding of how functional brain states emerge from their underlying structural substrate and how neurons and neural networks process information. Magnetic Resonance Imaging (MRI) offers a range of technique that enables the measurement of both, functional and structural connectivity. In this context, functional connectivity is defined as a correlation between remote neurophysiological events in temporal domain, while structural or anatomical connectivity refers to the physical pathways that connect the “nodes of the network”, i.e., the main white matter tracts of the brain. Characterising these properties non-invasively and defining the so-called “human connectome” has been the target of numerous efforts. This talk will provide an overview of the methods used for mapping brain connections, with a specific focus on the combination of structural and functional information. Moreover, we will discuss some of the limitations and the pitfalls of these techniques. • Bernadette Hahn, University of Würzburg Challenges in dynamic tomography. ABSTRACT Image reconstruction in standard tomography (CT, MRI, etc.) is well understood if the object under investigation is stationary during the data acquisition. However, this assumption is violated in many medical and industrial applications, e.g., due to patient and organ motion or while imaging fluid flow. Consequently, standard reconstruction techniques lead to motion artefacts in the computed images, e.g., blurring, ghosting, etc., which can significantly impede a viImage reconstruction in standard tomography (CT, MRI, etc.) is well understood if the object under investigation is stationary during the data acquisition. However, this assumption is violated in many medical and industrial applications, e.g., due to patient and organ motion or while imaging fluid flow. Consequently, standard reconstruction techniques lead to motion artefacts in the computed images, e.g., blurring, ghosting, etc., which can significantly impede a vi