Fundamenta Informaticae - Volume 165, issue 1

Authors: Ghassemi, Fatemeh | Fokkink, Wan

Article Type: Research Article

Abstract: Malfunctions of a mobile ad hoc network (MANET) protocol caused by a conceptual mistake in the protocol design, rather than unreliable communication, can often be detected only by considering communication among the nodes in the network to be reliable. In Restricted Broadcast Process Theory, which was developed for the specification and verification of MANET protocols, the communication operator is lossy. Replacing unreliable with reliable communication invalidates existing results for this process theory. We examine the effects of this adaptation on the semantics of the framework with regard to the non-blocking property of communication in MANETs, the notion of behavioral equivalence …relation and its axiomatization. To utilize our complete axiomatization for analyzing the correctness of protocols at the syntactic level, we introduce a precongruence relation which abstracts away from a sequence of multi-hop communications, leading to an application-level action preconditioned by a multi-hop constraint over the topology. We illustrate the applicability of our framework through a simple routing protocol. To prove its correctness, we introduce a novel proof process, based on our precongruence relation. Show more

Keywords: Mobile ad hoc network, restricted broadcast, process algebra, behavioral congruence, refinement

DOI: 10.3233/FI-2019-1775

Citation: Fundamenta Informaticae, vol. 165, no. 1, pp. 1-41, 2019

Authors: Kovács, László

Article Type: Research Article

Abstract: The theory of Formal Concept Analysis (FCA) provides efficient methods for conceptualization of formal contexts. The methods of FCA are applied mainly on the field of knowledge engineering and data mining. The key element in FCA applications is the generation of a concept set. The main goal of this research work is to develop an efficient incremental method for the construction of concept sets. The incremental construction method is used for problems where context may change dynamically. The paper first proposes a novel incremental concept set construction algorithm called ALINC, where the insertion loop runs over the attribute set. The …combination of object-level context processing and ALINC is an object level incremental algorithm (OALINC) where the context is built up object by object. Based on the performed tests, OALINC dominates the other popular batch or incremental methods for sparse contexts. For dense contexts, the OINCLOSE method, which uses the InClose algorithm for processing of reduced contexts, provides a superior efficiency. Regarding the OALINC/OINCLOSE algorithms, our test results with uniform distribution and real data sets show that our method provides very good performance in the full investigated parameter range. Especially good results are experienced for symmetric contexts in the case of word clustering using context-based similarity. Show more

Keywords: Formal Concept Analysis, concept set, incremental concept set generation, InClose method

DOI: 10.3233/FI-2019-1776

Citation: Fundamenta Informaticae, vol. 165, no. 1, pp. 43-73, 2019

Authors: Shaheen, Tanzeela | Stell, John G.

Article Type: Research Article

Abstract: We generalize the well-known correspondence between partitions and equivalence relations on a set to the case of graphs and hypergraphs. This is motivated by the role that partitions and equivalence relations play in Rough Set Theory and the results provide some of the foundations needed to develop a theory of rough graphs. We use one notion of a partition of a hypergraph, which we call a graphical partition, and we show how these structures correspond to relations on a hypergraph having additional properties. In the case of a hypergraph with only nodes and no edges these properties are exactly the …usual reflexivity, symmetry and transitivity properties required for equivalence relations on a set. We present definitions for upper and lower approximations of a subgraph with respect to a graphical partition. These generalize the well-known approximations in Rough Set Theory. We establish fundamental properties of our generalized approximations and provide examples of these constructions on some graphs. Show more

DOI: 10.3233/FI-2019-1777

Citation: Fundamenta Informaticae, vol. 165, no. 1, pp. 75-98, 2019