Fundamenta Informaticae - Volume 179, issue 2

Authors: Schlingloff, H. | Penczek, W.

Article Type: Other

DOI: 10.3233/FI-2021-2015

Citation: Fundamenta Informaticae, vol. 179, no. 2, pp. i-ii, 2021

Authors: Czaja, Ludwik

Article Type: Research Article

Abstract: Cause-effect structures are objects of a formal system devised for modeling, testing and verifying properties of tasks, where parallel execution of actions is the most characteristic feature. This is an algebraic system called a quasi-semiring. In this paper elementary cause-effect structures, a system behaviourally equivalent to 1-safe Petri nets, are extended by the following features: weighted edges, multi-valued nodes having capacities (counterpart of place/transition Petri nets), inhibitors and a model of time. The extensions are accomplished by modifying the notion of state and semantics, but leaving unchanged structure of the quasi-semiring expressions.

DOI: 10.3233/FI-2021-2016

Citation: Fundamenta Informaticae, vol. 179, no. 2, pp. 93-111, 2021

Authors: Akili, Samira | Weidlich, Matthias

Article Type: Research Article

Abstract: Complex event processing (CEP) evaluates queries over streams of event data to detect situations of interest. If the event data are produced by geographically distributed sources, CEP may exploit in-network processing that distributes the evaluation of a query among the nodes of a network. To this end, a query is modularized and individual query operators are assigned to nodes, especially those that act as data sources. Existing solutions for such operator placement, however, are limited in that they assume all query results to be gathered at one designated node, commonly referred to as a sink. Hence, existing techniques postulate a …hierarchical structure of the network that generates and processes the event data. This largely neglects the optimisation potential that stems from truly decentralised query evaluation with potentially many sinks. To address this gap, in this paper, we propose Multi-Sink Evaluation (MuSE) graphs as a formal computational model to evaluate common CEP queries in a decentralised manner. We further prove the completeness of query evaluation under this model. Striving for distributed CEP that can scale to large volumes of high-frequency event streams, we show how to reason on the network costs induced by distributed query evaluation and prune inefficient query execution plans. As such, our work lays the foundation for distributed CEP that is both, sound and efficient. Show more

Keywords: distributed systems, complex event processing, operator placement

DOI: 10.3233/FI-2021-2017

Citation: Fundamenta Informaticae, vol. 179, no. 2, pp. 113-134, 2021

Authors: Getir Yaman, Sinem | Pavese, Esteban | Grunske, Lars

Article Type: Research Article

Abstract: In this article, we introduce a probabilistic verification algorithm for stochastic regular expressions over a probabilistic extension of the Action based Computation Tree Logic (ACTL*). The main results include a novel model checking algorithm and a semantics on the probabilistic action logic for stochastic regular expressions (SREs). Specific to our model checking algorithm is that SREs are defined via local probabilistic functions. Such functions are beneficial since they enable to verify properties locally for sub-components. This ability provides a flexibility to reuse the local results for the global verification of the system; hence, the framework can be used for iterative …verification. We demonstrate how to model a system with an SRE and how to verify it with the probabilistic action based logic and present a preliminary performance evaluation with respect to the execution time of the reachability algorithm. Show more

Keywords: quantitative verification, probabilistic verification, formal models, stochastic regular expressions, probabilistic regular expressions, stochastic algebra, action based logic

DOI: 10.3233/FI-2021-2018

Citation: Fundamenta Informaticae, vol. 179, no. 2, pp. 135-163, 2021

Authors: Grabowski, Adam

Article Type: Research Article

Abstract: The paper contains some remarks on building automated counterpart of a comparison of some generalized rough approximations of sets, where the classical indiscernibility relation is generalized to arbitrary binary relation. Our focus was on translating rationality postulates for such operators by means of the Mizar system – the software and the database which allows for expressing and checking mathematical knowledge for the logical correctness. The main objective was the formal (and machine-checked) proof of Theorem 4.1 from A. Gomolińska’s paper “A Comparative Study of Some Generalized Rough Approximations ”, hence the present title. We provide also the discussion on how …to make the presentation more efficient to reuse the reasoning techniques of the Mizar verifier. Show more

Keywords: rough approximation, formalization of mathematics, Mizar Mathematical Library

DOI: 10.3233/FI-2021-2019

Citation: Fundamenta Informaticae, vol. 179, no. 2, pp. 165-182, 2021

Authors: Artiemjew, Piotr | Ropiak, Krzysztof

Article Type: Research Article

Abstract: One of the most popular families of techniques to boost classification are Ensemble methods. Random Forests, Bagging and Boosting are the most popular and widely used ones. This article presents a novel Ensemble Model, named Random Granular Reflections. The algorithm used in this new approach creates an ensemble of homogeneous granular decision systems. The first step of the learning process is to take the training system and cover it with random homogeneous granules (groups of objects from the same decision class that are as little indiscernible from each other as possible). Next, granular reflection is created, which is finally used …in the classification process. Results obtained by our initial experiments show that this approach is promising and comparable with other tested methods. The main advantage of our new method is that it is not necessary to search for optimal parameters while looking for granular reflections in the subsequent iterations of our ensemble model. Show more

Keywords: Random Granular Reflections, Homogeneous Granulation, CSG Classifier, Ensemble Model, Rough Sets, Decision Systems, Classification

DOI: 10.3233/FI-2021-2020

Citation: Fundamenta Informaticae, vol. 179, no. 2, pp. 183-203, 2021

Authors: Barbuti, Roberto | Bove, Pasquale | Gori, Roberta | Gruska, Damas | Levi, Francesca | Milazzo, Paolo

Article Type: Research Article

Abstract: Gene regulatory networks represent the interactions among genes regulating the activation of specific cell functionalities and they have been successfully modeled using threshold Boolean networks. In this paper we propose a systematic translation of threshold Boolean networks into reaction systems. Our translation produces a non redundant set of rules with a minimal number of objects. This translation allows us to simulate the behavior of a Boolean network simply by executing the (closed) reaction system we obtain. This can be very useful for investigating the role of different genes simply by “playing” with the rules. We developed a tool able to …systematically translate a threshold Boolean network into a reaction system. We use our tool to translate two well known Boolean networks modelling biological systems: the yeast-cell cycle and the SOS response in Escherichia coli. The resulting reaction systems can be used for investigating dynamic causalities among genes. Show more

DOI: 10.3233/FI-2021-2021

Citation: Fundamenta Informaticae, vol. 179, no. 2, pp. 205-225, 2021