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The use of Horizontal Subsurface Constructed Wetlands (HSCWs) for treating wastewaters in small communities has increased in the last years due to HSCW’s ecological singularities. Unfortunately, the same singularities that differentiate HSCWs complicate any attempt to develop models and produce generic decision-support systems for them. Classical mathematical and statistical approaches used in other Wastewater Treatment Plants do not properly fit the particularities of HSCW and provide little insight in the domain of HSCW. We introduce a novel approach based on logic-based declarative specifications, i.e. non-monotonic causal logic, to capture explicit and implicit knowledge about HSCWs. By expressing all the relevant aspects of a HSCW in a declarative way, we produce a logic-based model which captures features that other approaches fail to formalize. At the end, we produce a complete decision-support system based on that model and test it against a set of realistic scenarios validated by experts. We discuss in which aspects this approach performs better than the most commonly proposed solutions in the bibliography and why it does so., Peer Reviewed, Postprint (published version)

Las políticas de gestión de la calidad del agua a nivel de cuenca hidrográfica son especialmente importantes para la prevención y/o reducción de la polución originada por el hombre en el medio ambiente. Los efluentes industriales son un elemento prioritario particularmente en los Sistemas Urbanos de Aguas Residuales (SUAR) que reciben mezcladas las aguas residuales provenientes de viviendas particulares y de industrias, así como el agua de lluvia. En este artículo, presentamos un análisis y una implementación de agentes normativos que capturan las regulaciones específicas de las políticas Catalanas de prevención de la polución. La implementación de los agentes normativos está basada en el Cálculo de Situaciones. // Water quality management policies on a river basin scale are of special importance in order to prevent and/or reduce environmental pollution caused by human sources. Industrial effluents are a priority issue particularly in Urban Wastewater Systems (UWS) that receive mixed household and industrial wastewaters, apart from rainfall water. In this paper, we present an analysis and implementation of normative agents that capture concrete regulations of the Catalan pollution- prevention policies. The implementation of the normative agents is based on Situation Calculus., Peer Reviewed, Postprint (published version)

We look at a general way of inducing semantics in argumentation theory by means of a mapping defined on the family of 2-valued models of a normal program, which is constructed in terms of the argumentation framework. In this way we define a new argumentation semantics called stable abducible which lies in between the stable and the preferred semantics. The relevance of this new semantics is that it is nonempty for any argumentation framework, and coincides with the stable argumentation semantics whenever this is non-empty. We study some of the properties of this semant., Peer Reviewed, Postprint (published version)

Enterprise systems are increasingly composed of (and even functioning as) components in a dynamic, digital ecosystem. On the one hand, this new situation requires flexible, spontaneous and opportunistic collaboration activities to be identified and established among (electronic) business parties. On the other, it demands engineering methods that are able to integrate new functionalities and behaviours into running systems composed by active, distributed, interdependent processes. Here we present a multi-level architecture that combines organisational and coordination theories with model driven development, for the implementation, deployment and management of dynamic, flexible and robust service-oriented business applications, combined with a service layer that accommodates semantic service description, fine-grained semantic service discovery and the dynamic adaptation of services to meet changing circumstances, Peer Reviewed, Postprint (published version)

Default rules, i.e. statements of the form normally a’s are b’s, are usually handled in Answer Set Programming by means of negation as failure which provides a way to capture exceptions to normal situations. In this paper we propose another approach which offers an operational counterpart to negation as failure, and which may be thought as a corresponding dual attitude. The approach amounts to an explicit rewriting of exceptions in default rules, together with the addition of completion rules that are consistent with current knowledge. It is shown that the approach can be applied to restore the consistency of inconsistent programs that implicitly involve specificity ordering between the rules. The approach is compared to previous works aiming at providing support to the rewriting of default rules. It is also shown how the proposed approach agrees with the results obtained in the classical way., Peer Reviewed, Postprint (published version)

The use of knowledge-based systems has been shown to be a suitable approach to support decision making in environmental systems. Capturing and managing the huge quantity of data/information that has to be considered is an intrinsic factor that makes environmental systems a sophisticated domain. Organizing this data in a naive way can impact the efficacy of any knowledge-based system. Another intrinsic factor is the variety of data sources, which can result in inconsistent, uncertain or incomplete knowledge bases when different data sources are considered. Accordingly, two central issues of a successful knowledge-based system are the organization of its knowledge base and the expressiveness of its specification language. In this paper, we introduce a stratified framework for structuring any environmental knowledge base. We will argue that a declarative specification language, such as Answer Set Programming, is expressive enough to capture environmental knowledge bases that are inconsistent, uncertain and incomplete. We also present an automata-based approach to manage actions in knowledge-based systems. By solving a use case, specifically the diagnosis of the safety of a particular industrial wastewater discharge in an urban wastewater system, we illustrate how to represent relevant abstractions to model related complex processes. We show that by using them it is also possible to automate the diagnosis process (in the present case, for example, to diagnose problems at a wastewater treatment plant and afterward in the river) and hence support the decision-making task., Peer Reviewed, Postprint (published version)

Intelligent systems that assist users in fulfilling complex tasks need a concise and processable representation of incomplete and uncertain information. In order to be able to choose among different options, these systems also need a compact and processable representation of the concept of preference. Preferences can provide an effective way to choose the best solutions to a given problem. These solutions can represent the most plausible states of the world when we model incomplete information, the most satisfactory states of the world when we express user preferences, or optimal decisions when we make decisions under uncertainty. Several domains, such as, reasoning under incomplete and uncertain information, user preference modeling, and qualitative decision making under uncertainty, have benefited from advances on preference representation. In the literature, several symbolic approaches of nonclassical reasoning have been proposed. Among them, logic programming under answer set semantics offers a good compromise between symbolic representation and computation of knowledge and several extensions for handling preferences. Nevertheless, there are still some open issues to be considered in logic programming. In nonmonotonic reasoning, first, most approaches assume that exceptions to logic program rules are already specified. However, sometimes, it is possible to consider implicit preferences based on the specificity of the rules to handle incomplete information. Secondly, the joint handling of exceptions and uncertainty has received little attention: when information is uncertain, the selection of default rules can be a matter of explicit preferences and uncertainty. In user preference modeling, although existing logic programming specifications allow to express user preferences which depend both on incomplete and contextual information, in some applications, some preferences in some context may be more important than others. Furthermore, more complex preference expre, Els sistemes intel.ligents que assisteixen a usuaris en la realització de tasques complexes necessiten una representació concisa i formal de la informació que permeti un raonament nomonòton en condicions d’incertesa. Per a poder escollir entre les diferents opcions, aquests sistemes solen necessitar una representació del concepte de preferència. Les preferències poden proporcionar una manera efectiva de triar entre les millors solucions a un problema. Aquestes solucions poden representar els estats del món més plausibles quan es tracta de modelar informació incompleta, els estats del món més satisfactori quan expressem preferències de l’usuari, o decisions òptimes quan estem parlant de presa de decisió incorporant incertesa. L’ús de les preferències ha beneficiat diferents dominis, com, el raonament en presència d’informació incompleta i incerta, el modelat de preferències d’usuari, i la presa de decisió sota incertesa. En la literatura, s’hi troben diferents aproximacions al raonament no clàssic basades en una representació simbòlica de la informació. Entre elles, l’enfocament de programació lògica, utilitzant la semàntica de answer set, ofereix una bona aproximació entre representació i processament simbòlic del coneixement, i diferents extensions per gestionar les preferències. No obstant això, en programació lògica es poden identificar diferents problemes pel que fa a la gestió de les preferències. Per exemple, en la majoria d’enfocaments de raonament no-monòton s’assumeix que les excepcions a default rules d’un programa lògic ja estan expressades. Però de vegades es poden considerar preferències implícites basades en l’especificitat de les regles per gestionar la informació incompleta. A més, quan la informació és també incerta, la selecció de default rules pot dependre de preferències explícites i de la incertesa. En el modelatge de preferències del usuari, encara que els formalismes existents basats en programació lògica permetin expressar preferències que de, Los sistemas inteligentes que asisten a usuarios en tareas complejas necesitan una representación concisa y procesable de la información que permita un razonamiento nomonótono e incierto. Para poder escoger entre las diferentes opciones, estos sistemas suelen necesitar una representación del concepto de preferencia. Las preferencias pueden proporcionar una manera efectiva para elegir entre las mejores soluciones a un problema. Dichas soluciones pueden representar los estados del mundo más plausibles cuando hablamos de representación de información incompleta, los estados del mundo más satisfactorios cuando hablamos de preferencias del usuario, o decisiones óptimas cuando estamos hablando de toma de decisión con incertidumbre. El uso de las preferencias ha beneficiado diferentes dominios, como, razonamiento en presencia de información incompleta e incierta, modelado de preferencias de usuario, y toma de decisión con incertidumbre. En la literatura, distintos enfoques simbólicos de razonamiento no clásico han sido creados. Entre ellos, la programación lógica con la semántica de answer set ofrece un buen acercamiento entre representación y procesamiento simbólico del conocimiento, y diferentes extensiones para manejar las preferencias. Sin embargo, en programación lógica se pueden identificar diferentes problemas con respecto al manejo de las preferencias. Por ejemplo, en la mayoría de enfoques de razonamiento no-monótono se asume que las excepciones a default rules de un programa lógico ya están expresadas. Pero, a veces se pueden considerar preferencias implícitas basadas en la especificidad de las reglas para manejar la información incompleta. Además, cuando la información es también incierta, la selección de default rules pueden depender de preferencias explícitas y de la incertidumbre. En el modelado de preferencias, aunque los formalismos existentes basados en programación lógica permitan expresar preferencias que dependen de información contextual e incompleta, Sistemi intelligenti, destinati a fornire supporto agli utenti in processi decisionali complessi, richiedono una rappresentazione dell’informazione concisa, formale e che permetta di ragionare in maniera non monotona e incerta. Per poter scegliere tra le diverse opzioni, tali sistemi hanno bisogno di disporre di una rappresentazione del concetto di preferenza altrettanto concisa e formale. Le preferenze offrono una maniera efficace per scegliere le miglior soluzioni di un problema. Tali soluzioni possono rappresentare gli stati del mondo più credibili quando si tratta di ragionamento non monotono, gli stati del mondo più soddisfacenti quando si tratta delle preferenze degli utenti, o le decisioni migliori quando prendiamo una decisione in condizioni di incertezza. Diversi domini come ad esempio il ragionamento non monotono e incerto, la strutturazione del profilo utente, e i modelli di decisione in condizioni d’incertezza hanno tratto beneficio dalla rappresentazione delle preferenze. Nella bibliografia disponibile si possono incontrare diversi approcci simbolici al ragionamento non classico. Tra questi, la programmazione logica con answer set semantics offre un buon compromesso tra rappresentazione simbolica e processamento dell’informazione, e diversi estensioni per la gestione delle preferenze sono state proposti in tal senso. Nonostante ció, nella programmazione logica esistono ancora delle problematiche aperte. Prima di tutto, nella maggior parte degli approcci al ragionamento non monotono, si suppone che nel programma le eccezioni alle regole siano già specificate. Tuttavia, a volte per trattare l’informazione incompleta è possibile prendere in considerazione preferenze implicite basate sulla specificità delle regole. In secondo luogo, la gestione congiunta di eccezioni e incertezza ha avuto scarsa attenzione: quando l’informazione è incerta, la scelta di default rule può essere una questione di preferenze esplicite e d’incertezza allo stesso tempo. Nella crea, Postprint (published version)

According to the Electric Power Research Institute (EPRI) a common semantics model is necessary for achieving interoperability in the Smart Grid vision. In this paper, we present an outline of two influential International Electrotech-nical Commission Standards (CIM and IEC 61850) for building a common semantic model in a Smart Grid vision. In addition, we revise two representative approaches suggested by EPRI for harmonizing these standards in a common semantic model. The pros and cons between these two approaches are identified and analyzed, Peer Reviewed, Postprint (published version)

This work is motivated by the difficulty of representing Environmental domains in a functional way. We present a formalization approach covering both environmental and computational needs. It allows us to produce an operational software for intelligent decision support on a Horizontal Subsurface Constructed Wetlands (HSCW) while capturing the most significant elements of the domain., Peer Reviewed, Postprint (published version)

In this paper we define a class of nested logic programs, nested logic programs with ordered disjunction (LPODs+), which allows to specify qualitative preferences by means of nested preference expressions. For doing this we extend the syntax of logic programs with ordered disjunction (LPODs) to capture more general expressions. We define the LPODs+ semantics in a simple way and we extend most of the results of logic programs with ordered disjunction showing how our approach effectively is a proper generalisation of LPODs., Peer Reviewed, Postprint (published version)

The management of Urban Wastewater Systems (UWS) is a critical and difficult process. Handling polluted water in UWS requires planning and decision making regarding sectors such as environmental, energetic, industrial, etc. In order to represent all the significant concepts, a powerful and flexible formalism is needed. Nowadays, there are solid approaches based on nonmonotonic reasoning which can capture dynamic domains such UWS. In this paper, we present an implementation of a real UWS in the action language Causal Calculator (CCalc-C+) which displays all the singularities of such domain and within which complex queries can be performed. The nonmonotonic causal theory, upon which is based CCalc, allows us to represent some characteristics of UWS such as nondeterministic actions and indirect effects of actions. We will capture the situations and the transitions of the UWS domain and represent them in the form of a finite state machine. CCalc allows us to perform queries regarding; the effects of actions, action planning to reach a certain state and path finding. The resultant work can be used in actual UWS to aid at the decision making process, simplifying the reasoning about actions and allowing a close representation of the real state of UWS., Peer Reviewed, Postprint (published version)

C+ is an action language for specifying and reasoning about the e ects of actions and the persistence of facts over time. Based on it. we present CN+, an operational enhanced form of C+ designed for representing complex normative systems and integrate them easily into the semantics of the causal theory of actions. The proposed system contains a particular formalization of norms using a life-cycle approach to capture the whole normative meaning of a complex normative framework. We discuss this approach and illustrate it with examples., Peer Reviewed, Postprint (author’s final draft)

Logic programs with possibilistic ordered disjunction (or LPPODs) are a recently defined logic-programming framework based on logic programs with ordered disjunction and possibilistic logic. The framework inherits the properties of such formalisms and merging them, it supports a reasoning which is nonmonotonic, preference-and uncertain-aware. The LPPODs syntax allows to specify 1) preferences in a qualitative way, and 2) necessity values about the certainty of program clauses. As a result at semantic level, preferences and necessity values can be used to specify an order among program solutions. This class of program therefore fits well in the representation of decision problems where a best option has to be chosen taking into account both preferences and necessity measures about information. In this paper we study the computation and the complexity of the LPPODs semantics and we describe the algorithm for its implementation following on Answer Set Programming approach. We describe some decision scenarios where the solver can be used to choose the best solutions by checking whether an outcome is possibilistically preferred over another considering preferences and uncertainty at the same time., Postprint (published version)

Water quality management policies on a river basin scale are of special importance in order to prevent and/or reduce pollution of several human sources into the environment. Industrial effluents represent a priority issue particularly in Urban Wastewater Systems (UWS) that receive mixed household and industrial wastewaters, apart from rainfall water. In this paper, we present an analysis and an implementation of normative agents which capture concrete regulations of the Catalan pollution-prevention policies. The implementation of the normative agents is based on situation calculus., Peer Reviewed, Postprint (published version)

Extension-based argumentation semantics have shown to be a suitable approach for performing practical reasoning. Since extension-based argumentation semantics were formalized in terms of relationships between atomic arguments, it has been shown that extension-based argumentation semantics based on admissible sets such as stable semantics can be characterized in terms of answer sets. In this paper, we present an approach for characterizing SCC-recursive semantics in terms of answer set models. In particular, we will show a characterization of CF2 in terms of answer set models. This result suggests that not only extension-based argumentation semantics based on admissible sets can be characterized in terms of answer sets; but also extension-based argumentation semantics based on Strongly Connected Components can be characterized in terms of answer sets., Peer Reviewed, Preprint

This paper presents an agent-based methodological approach to design distributed service-oriented systems which can adapt their behaviour according to changes in the environment and in the user needs, even taking the initiative to make suggestions and proactive choices. The highly dynamic, regulated, complex nature of the distributed, interconnected services is tackled through a methodological framework composed of three interconnected levels. The framework relies on coordination and organisational techniques, as well as on semantically annotated Web services to design, deploy and maintain a distributed system, using both a top-down and bottom-up approach. We present results based on a real use case: interactive community displays with tourist information and services, dynamically personalised according to user context and preferences., Preprint

We present an overview on how to perform non-monotonic reasoning based on paraconsistent logics. In particular, we show that one can define a logic programming semantics based on the paraconsistent logic G’3 which is called G’3-stable semantics. This semantics defines a frame for performing non-monotonic reasoning in domains which are pervaded with vagueness and inconsistencies. In fact, we show that, by considering also a possibilistic logic point of view, one can use this extended framework for defining a possibilistic logic programming approach able to deal with reasoning, which is at the same time non-monotonic and uncertain., Peer Reviewed, Postprint (published version)

Interconnected service providers constitute a highly dynamic, complex, distributed environment. Multi-agent system design-methodologies have been try-ing to address this kind of environments for a long time. The European project ALIVE presents a framework of three interconnected levels that tackles this issue relying on organisation and coordination techniques, as well as on developments in the Web-services world. This paper presents initial results focused on a high-tech, real use case: interactive community displays with touristic information and services, dynamically personalized according to user preferences and local laws., Peer Reviewed, Preprint

Extension-based argumentation semantics have been shown to be a suitable approach for performing practical reasoning. Since extension-based argumentation semantics were formalized in terms of relationships between atomic arguments, it has been shown that extension-based argumentation semantics (such as the grounded semantics and stable semantics) can be characterized by logic programming semantics with negation as failure. Recently, it has been shown that argumentation semantics such as the preferred semantics and the CF2 semantics can be characterized in terms of logic programming semantics. In this paper, we make a short overview w.r.t. recent results in the close relationship between extension-based semantics and logic programming semantics with negation as failure. We also show that there is enough evidence to believe that the use of declarative approaches based on logic programming semantics with negation as failure is a practical approach for performing practical reasoning following an argumentation reasoning approach., Peer Reviewed, Postprint (published version)

It is well-known that the management of Urban Wastewater Systems (UWS) is a complex and critical process. To decide which is the correct sequence of actions for managing a given circumstance it is necessary a sophisticated analysis of hypothetical impact of these. Hence, the design of intelligent systems able to perform temporal projections based on the description of actions could help to deal with risk scenarios. In this paper, we propose to use recent developments in knowledge representation languages and non-monotonic reasoning methodologies for representing and reasoning about actions for the Management of Urban Wastewater Systems. To this end, we explore the use of an action representation language called A for reasoning about the actions in the management of UWS. In particular, we consider the problem of industrial discharges. We present a declarative representation of a transition function from states and actions to states which allows us to make conclusions about a particular situation that may arise if one performs a particular sequence of actions., Peer Reviewed, Postprint (published version)

This paper presents an approach for specifying user preferences related to services by means of a preference meta-model, which is mapped to logic programs with possibilistic ordered disjunction following a Model-Driven Methodology (MDM). MDM allows to specify problem domains by means of meta-models which can be converted to instance models or other meta-models through transformation functions. In particular we propose a preference meta-model that defines an abstract preference specification language allowing users to specify preferences in a more friendly way using models. We also present a meta-model for logic programs with possibilistic order disjunction. Then we show how we conceptually map the preference meta-model to logic programs with possibilistic ordered disjunction by means of a mapping function., Peer Reviewed, Postprint (published version)

In this paper, by considering the idea that argumentation semantics can be viewed as a special form of logic programming semantics with negation as failure, we show that any logic programming semantics as the stable model semantics, the minimal models, etc., can define candidate argumentation semantics. These new argumentation semantics will overcome some of the problems of the Dung's argumentation semantics that have been discussed in the literature. The new argumentation semantics are based on a new recursive framework for logic programming semantics. This framework generalizes any logic programming semantics in order to build logic programming semantics which are always defined, satisfy the property of relevance and agree with the stable semantics for the class of stratified programs., Postprint (published version)

One of the most representative semantics of Dung's approach is the grounded semantics. This semantics captures a skeptical approach, this means that given an argumentation framework the grounded semantics always identifies a single set of arguments, called grounded extension. It worth mentioning that the grounded semantics approach is one of the most useful argumentation approaches in real argumentation-based systems As argumentation can be abstractly defined as the interaction of arguments for and against some conclusion, a reasoning based on an abstract argumentation semantics for describing the interaction arguments is as important as to find an extension of an argumentation framework. In this paper, we introduce a novel formal argumentation method based on normal programs and rewriting systems which is able to - describe the interaction of arguments during the process of inferring an extension, and -define extensions of the grounded semantics based on specific rewriting rules which perform particular kind of reasoning as in reasoning by cases. Moreover, we point out that our codification of an argumentation framework as a normal program is a suitable codification for studying other abstract argumentation semantics as are the stable semantics and the preferred semantics., Postprint (author's final draft)

Given an argumentation framework AF, we present a normal program Psi_{AF}, such that the preferred extensions of AF correspond exactly with the pstable models of Psi_{AF}. Moreover, we motivate the notion of suitable codifications for developing metainterpreters of argumentation theory based on logic programming., Postprint (published version)

The management of Urban Wastewater Systems (UWS) is a critical and difficult process. Handling polluted water in UWS requires planning and decision making regarding sectors such as environmental, energetic, industrial, etc. In order to represent all the significant concepts, a powerful and flexible formalism is needed. Nowadays, there are solid approaches based on nonmonotonic reasoning which can capture dynamic domains such UWS. In this paper, we present an implementation of a real UWS in the action language Causal Calculator (CCalc-C+) which displays all the singularities of such domain and within which complex queries can be performed. The nonmonotonic causal theory, upon which is based CCalc, allows us to represent some characteristics of UWS such as nondeterministic actions and indirect effects of actions. We will capture the situations and the transitions of the UWS domain and represent them in the form of a finite state machine. CCalc allows us to perform queries regarding; the effects of actions, action planning to reach a certain state and path finding. The resultant work can be used in actual UWS to aid at the decision making process, simplifying the reasoning about actions and allowing a close representation of the real state of UWS., Peer Reviewed, Postprint (published version)