Open Access
Arquitectura de publicación automatizada de contenidos educativos supervisados en Internet
(1999) Arin Irastorza, María Asunción; Magaña Lizarrondo, Eduardo; Astrain Escola, José Javier; Villadangos Alonso, Jesús; González de Mendívil Moreno, José Ramón; Automática y Computación; Automatika eta Konputazioa
This paper presents an automated publishing architecture of educational and supervised contents over the Internet. The system makes easier the job of publishing educational courses over the network using specific tools that automates the access control (CGI -- Common Gateway Interface), encrypts the information that goes through the net for not being accessed by strangers (SSL – Secure Sockets Layer), gives an statistical control of the usage of the system, and tutors the course. This project is multiplatform, i.e. all the components that integrate the system are available for any operating system (Windows 9X, Solaris, Linux,...) and it is based on the Web.
Open Access
Adjusting fuzzy automata for string similarity measuring
(EUSFLAT, 2001) Astrain Escola, José Javier; Villadangos Alonso, Jesús; González de Mendívil Moreno, José Ramón; Garitagoitia Padrones, José Ramón; Fariña Figueredo, Federico; Ingeniería Matemática e Informática; Matematika eta Informatika Ingeniaritza; Automática y Computación; Automatika eta Konputazioa
In this paper, we introduce a fuzzy automaton for computing the similarity between pairs of strings and a genetic method for adjusting its parameters. The fuzzy automaton models the edit operations needed to transform any string into another one. The selection of appropriate fuzzy operations and fuzzy membership values for the transitions leads to improve the system performance for a particular application.
Embargo
Finite determinization of fuzzy automata using a parametric product-based t-norm
(Elsevier, 2024) Micic, Ivana; Stanimirovic, Stefan; González de Mendívil Moreno, José Ramón; Ciric, Miroslav; Jancic, Zorana; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute of Smart Cities - ISC
This paper presents a novel approach for the approximate determinization of fuzzy automata over the product structure. We introduce the parametric modification of the product t-norm in the pre-determinization setting. On the one hand, the behavior of a fuzzy automaton over the parametric t-norm differs from the behavior of the fuzzy automaton over the product t-norm only in words with a degree of acceptance below the given parameter. However, using the parametric t-norm, we obtain an algorithm that outputs a finite minimal deterministic fuzzy automaton whose behavior differs from the starting fuzzy automaton described above. By setting the parameter to a sufficiently small value, the proposed algorithm provides a deterministic fuzzy automaton with behavior that differs insignificantly from the starting fuzzy automaton, as the difference is achieved only for words accepted by the starting fuzzy automaton with an insignificant value. As a tradeoff, the proposed approach provides finite determinization, even when all other determinization methods would result in an infinite deterministic automaton. We support this fact with an illustrative example.
Embargo
Polynomial crisp-minimization algorithm for fuzzy deterministic automata
(Elsevier, 2024-11-01) González de Mendívil Grau, Aitor; Fariña Figueredo, Federico; Stanimirovic, Stefan; Micic, Ivana; González de Mendívil Moreno, José Ramón; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute of Smart Cities - ISC
Designing automata minimization algorithms is a significant topic in Automata Theory and Languages with practical applications. In this paper, we develop an efficient minimization algorithm for deterministic fuzzy finite automata over locally finite lattices. More precisely, the algorithm outputs an equivalent minimal crisp-deterministic fuzzy finite automaton for an input fuzzy deterministic finite automaton (FDfA). The running time of the proposed algorithm is polynomial for particular types of locally finite lattices, specifically for max-min-based complete residuated lattices. The intuition behind the proposed algorithm relies on the polynomial minimization algorithm's intuition for ordinary deterministic automata developed by Vazquez de Parga, Garcia, and Lopez (2013) [35]. The motivation for this study comes from the fact that the original algorithm's notions and meanings are lost in the context of fuzzy automata. Thus, we establish a new theoretical foundation that provides the correctness and the polynomial-time nature of this new crisp-minimization algorithm for FDfAs.
Open Access
Finite Nerode construction for fuzzy automata over the product algebra
(Springer, 2023) Jancic, Zorana; Micic, Ivana; Stanimirovic, Stefan; González de Mendívil Moreno, José Ramón; Ciric, Miroslav; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika
The Nerode's automaton of a given fuzzy automaton A is a crisp-deterministic fuzzy automaton obtained by determinization of A using the well-known accessible fuzzy subset construction. This celebrated construction of a crisp-deterministic fuzzy automaton has served as a basis for various determinization procedures for fuzzy automata. However, the drawback of this construction is that it may not be feasible when the underlying structure for fuzzy automata is the product algebra because it is not locally finite. This paper provides an alternative way to construct a Nerode-like fuzzy automaton when the input fuzzy automaton is defined over the product algebra. This construction is always finite, since the fuzzy language recognized by this fuzzy automaton has a finite domain. However, this new construction does not accept the same fuzzy language as the initial fuzzy automaton. Nonetheless, it differs only in words accepted to some very small degree, which we treat as irrelevant. Therefore, our construction is an excellent finite approximation of Nerode's automaton.
Open Access
Conditions for the existence of maximal factorizations
(Elsevier, 2020) Gerdjikov, Stefan; González de Mendívil Moreno, José Ramón; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika
Extending classical algorithms for ordinary weighted or string-to-string automata to automata with underlying more general algebraic structures is of significant practical and theoretical interest. However, the generalization of classical algorithms sets certain assumptions on the underlying structure. In this respect the maximal factorization turns out to be a sufficient condition for many practical problems, e.g. minimization and canonization. Recently, an axiomatic approach on monoid structures suggested that monoids with most general equalizer (mge-monoids) provide an alternative framework to achieve similar results. In this paper, we study the fundamental relation between monoids admitting a maximal factorization and mge-monoids. We describe necessary conditions for the existence of a maximal factorization and provide sufficient conditions for an mge-monoid to admit a maximal factorization.
Open Access
CAP theorem: revision of its related consistency models
(Oxford University Press, 2019) Muñoz Escoí, Francesc D.; Juan Marín, Rubén de; García Escrivá, José Ramón; González de Mendívil Moreno, José Ramón; Bernabéu Aubán, José M.; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika
The CAP theorem states that only two of these properties can be simultaneously guaranteed in a distributed service: (i) consistency, (ii) availability, and (iii) network partition tolerance. This theorem was stated and proved assuming that “consistency” refers to atomic consistency. However, multiple consistency models exist and atomic consistency is located at the strongest edge of that spectrum. Many distributed services deployed in cloud platforms should be highly available and scalable. Network partitions may arise in those deployments and should be tolerated. One way of dealing with CAP constraints consists in relaxing consistency. Therefore, it is interesting to explore the set of consistency models not supported in an available and partition-tolerant service (CAP-constrained models). Other weaker consistency models could be maintained when scalable services are deployed in partitionable systems (CAP-free models). Three contributions arise: (1) multiple other CAPconstrained models are identified, (2) a borderline between CAP-constrained and CAP-free models is set, and (3) a hierarchy of consistency models depending on their strength and convergence is built.
Open Access
Eventual consistency: origin and support
(Slovak Academy of Sciences, Institute of Informatics, 2018) Muñoz Escoí, Francesc D.; García Escrivá, José Ramón; Sendra Roig, Juan Salvador; Bernabéu Aubán, José M.; González de Mendívil Moreno, José Ramón; Ingeniería Matemática e Informática; Matematika eta Informatika Ingeniaritza
Eventual consistency is demanded nowadays in geo-replicated services that need to be highly scalable and available. According to the CAP constraints, when network partitions may arise, a distributed service should choose between being strongly consistent or being highly available. Since scalable services should be available, a relaxed consistency (while the network is partitioned) is the preferred choice. Eventual consistency is not a common data-centric consistency model, but only a state convergence condition to be added to a relaxed consistency model. There are still several aspects of eventual consistency that have not been analysed in depth in previous works: 1. which are the oldest replication proposals providing eventual consistency, 2. which replica consistency models provide the best basis for building eventually consistent services, 3. which mechanisms should be considered for implementing an eventually consistent service, and 4. which are the best combinations of those mechanisms for achieving different concrete goals. This paper provides some notes on these important topics.