Departament de Ciències de la Computació
http://hdl.handle.net/2117/3971
2018-02-19T01:00:12ZThe parallel complexity of positive linear programming
http://hdl.handle.net/2117/114140
The parallel complexity of positive linear programming
Trevisan, Luca; Xhafa Xhafa, Fatos
In this paper we study the parallel complexity of Positive Linear Programming (PLP), i.e. the special case of Linear Programming in packing/covering form where the input constraint matrix and constraint vector consist entirely of positive entries. We show that the problem of exactly solving PLP is P-complete.
2018-02-15T11:36:16ZTrevisan, LucaXhafa Xhafa, FatosIn this paper we study the parallel complexity of Positive Linear Programming (PLP), i.e. the special case of Linear Programming in packing/covering form where the input constraint matrix and constraint vector consist entirely of positive entries. We show that the problem of exactly solving PLP is P-complete.Open source software ecosystems : a systematic mapping
http://hdl.handle.net/2117/114102
Open source software ecosystems : a systematic mapping
Franco Bedoya, Óscar Hernán; Ameller, David; Costal Costa, Dolors; Franch Gutiérrez, Javier
Context: Open source software (OSS) and software ecosystems (SECOs) are two consolidated research areas in software engineering. OSS influences the way organizations develop, acquire, use and commercialize software. SECOs have emerged as a paradigm to understand dynamics and heterogeneity in collaborative software development. For this reason, SECOs appear as a valid instrument to analyze OSS systems. However, there are few studies that blend both topics together. Objective: The purpose of this study is to evaluate the current state of the art in OSS ecosystems (OSSECOs) research, specifically: (a) what the most relevant definitions related to OSSECOs are; (b) what the particularities of this type of SECO are; and (c) how the knowledge about OSSECO is represented. Method: We conducted a systematic mapping following recommended practices. We applied automatic and manual searches on different sources and used a rigorous method to elicit the keywords from the research questions and selection criteria to retrieve the final papers. As a result, 82 papers were selected and evaluated. Threats to validity were identified and mitigated whenever possible. Results: The analysis allowed us to answer the research questions. Most notably, we did the following: (a) identified 64 terms related to the OSSECO and arranged them into a taxonomy; (b) built a genealogical tree to understand the genesis of the OSSECO term from related definitions; (c) analyzed the available definitions of SECO in the context of OSS; and (d) classified the existing modelling and analysis techniques of OSSECOs. Conclusion: As a summary of the systematic mapping, we conclude that existing research on several topics related to OSSECOs is still scarce (e.g., modelling and analysis techniques, quality models, standard definitions, etc.). This situation calls for further investigation efforts on how organizations and OSS communities actually understand OSSECOs.
2018-02-14T09:08:51ZFranco Bedoya, Óscar HernánAmeller, DavidCostal Costa, DolorsFranch Gutiérrez, JavierContext: Open source software (OSS) and software ecosystems (SECOs) are two consolidated research areas in software engineering. OSS influences the way organizations develop, acquire, use and commercialize software. SECOs have emerged as a paradigm to understand dynamics and heterogeneity in collaborative software development. For this reason, SECOs appear as a valid instrument to analyze OSS systems. However, there are few studies that blend both topics together. Objective: The purpose of this study is to evaluate the current state of the art in OSS ecosystems (OSSECOs) research, specifically: (a) what the most relevant definitions related to OSSECOs are; (b) what the particularities of this type of SECO are; and (c) how the knowledge about OSSECO is represented. Method: We conducted a systematic mapping following recommended practices. We applied automatic and manual searches on different sources and used a rigorous method to elicit the keywords from the research questions and selection criteria to retrieve the final papers. As a result, 82 papers were selected and evaluated. Threats to validity were identified and mitigated whenever possible. Results: The analysis allowed us to answer the research questions. Most notably, we did the following: (a) identified 64 terms related to the OSSECO and arranged them into a taxonomy; (b) built a genealogical tree to understand the genesis of the OSSECO term from related definitions; (c) analyzed the available definitions of SECO in the context of OSS; and (d) classified the existing modelling and analysis techniques of OSSECOs. Conclusion: As a summary of the systematic mapping, we conclude that existing research on several topics related to OSSECOs is still scarce (e.g., modelling and analysis techniques, quality models, standard definitions, etc.). This situation calls for further investigation efforts on how organizations and OSS communities actually understand OSSECOs.Verb similarity: Comparing corpus and psycholinguistic data
http://hdl.handle.net/2117/114071
Verb similarity: Comparing corpus and psycholinguistic data
Gil-Vallejo, Lara; Coll-Florit, Marta; Castellón Masalles, Irene; Turmo Borras, Jorge
Similarity, which plays a key role in fields like cognitive science, psycho-
linguistics and natural language processing, is a broad and multifaceted concept. In this work we analyse how two approaches that belong to different perspectives, the corpus view and the psycholinguistic view, articulate similarity between verb senses in Spanish. Specifically, we compare the similarity between verb senses based on their argument structure, which is captured through semantic roles, with their similarity defined by word associations. We address the question of whether verb argument structure, which reflects the expression of the events, and word associations, which are related to the speakers’ organization of the mental lexicon, shape similarity between verbs in a congruent manner, a topic which has not been explored previously. While we find significant correlations between verb sense similarities obtained from these two approaches, our findings also highlight some discrepancies between them and the importance of the degree of abstraction of the corpus annotation and psycholinguistic representations.
2018-02-13T10:05:48ZGil-Vallejo, LaraColl-Florit, MartaCastellón Masalles, IreneTurmo Borras, JorgeSimilarity, which plays a key role in fields like cognitive science, psycho-
linguistics and natural language processing, is a broad and multifaceted concept. In this work we analyse how two approaches that belong to different perspectives, the corpus view and the psycholinguistic view, articulate similarity between verb senses in Spanish. Specifically, we compare the similarity between verb senses based on their argument structure, which is captured through semantic roles, with their similarity defined by word associations. We address the question of whether verb argument structure, which reflects the expression of the events, and word associations, which are related to the speakers’ organization of the mental lexicon, shape similarity between verbs in a congruent manner, a topic which has not been explored previously. While we find significant correlations between verb sense similarities obtained from these two approaches, our findings also highlight some discrepancies between them and the importance of the degree of abstraction of the corpus annotation and psycholinguistic representations.Uncertainty in basic short-term macroeconomic models with angel-daemon games
http://hdl.handle.net/2117/114068
Uncertainty in basic short-term macroeconomic models with angel-daemon games
Gabarró Vallès, Joaquim; Serna Iglesias, María José
We propose the use of an angel-daemon framework to perform an uncertainty analysis of short-term macroeconomic models. The angel-daemon framework defines a strategic game where two agents, the angel and the daemon, act selfishly. These games are defined over an uncertainty profile which presents a short and macroscopic description of a perturbed situation. The Nash equilibria on these games provide stable strategies in perturbed situations, giving a natural estimation of uncertainty. We apply the framework to the uncertainty analysis of linear versions of the IS-LM and the IS-MP models.
2018-02-12T18:31:46ZGabarró Vallès, JoaquimSerna Iglesias, María JoséWe propose the use of an angel-daemon framework to perform an uncertainty analysis of short-term macroeconomic models. The angel-daemon framework defines a strategic game where two agents, the angel and the daemon, act selfishly. These games are defined over an uncertainty profile which presents a short and macroscopic description of a perturbed situation. The Nash equilibria on these games provide stable strategies in perturbed situations, giving a natural estimation of uncertainty. We apply the framework to the uncertainty analysis of linear versions of the IS-LM and the IS-MP models.Distributed ambient graphs with business configurations
http://hdl.handle.net/2117/114025
Distributed ambient graphs with business configurations
Mylonakis Pascual, Nicolás
In this paper we present distributed ambient graphs with business configurations to extend our original model of service oriented computing ($SOC$) with an ambient topology of locations. This ambient topology is based on the graph semantics of an adaptation of the ambient calculus. Thus, in this new service oriented model we can formalize all the external sites that take place in a service oriented application. Each site providing a service to a given service oriented application, will have its own business activity and it will have the possibility to transfer events with the service oriented application. Additionally, providing services can of course also require services to external sites. In this approach, we can also model several service oriented applications developed in different external sites. Thus, the resulting formalism allow us to perform choreographies.
2018-02-12T09:54:06ZMylonakis Pascual, NicolásIn this paper we present distributed ambient graphs with business configurations to extend our original model of service oriented computing ($SOC$) with an ambient topology of locations. This ambient topology is based on the graph semantics of an adaptation of the ambient calculus. Thus, in this new service oriented model we can formalize all the external sites that take place in a service oriented application. Each site providing a service to a given service oriented application, will have its own business activity and it will have the possibility to transfer events with the service oriented application. Additionally, providing services can of course also require services to external sites. In this approach, we can also model several service oriented applications developed in different external sites. Thus, the resulting formalism allow us to perform choreographies.Construct, merge, solve and adapt versus large neighborhood search for solving the multi-dimensional Knapsack problem: Which one works better when?
http://hdl.handle.net/2117/114023
Construct, merge, solve and adapt versus large neighborhood search for solving the multi-dimensional Knapsack problem: Which one works better when?
Lizárraga Olivas, Evelia; Blesa Aguilera, Maria Josep; Blum, Christian
Both, Construct, Merge, Solve and Adapt (CMSA) and Large Neighborhood Search (LNS), are hybrid algorithms that are based on iteratively solving sub-instances of the original problem instances, if possible, to optimality. This is done by reducing the search space of the tackled problem instance in algorithm-specific ways which differ from one technique to the other. In this paper we provide first experimental evidence for the intuition that, conditioned by the way in which the search space is reduced, LNS should generally work better than CMSA in the context of problems in which solutions are rather large, and the opposite is the case for problems in which solutions are rather small. The size of a solution is hereby measured by the number of components of which the solution is composed, in comparison to the total number of solution components. Experiments are conducted in the context of the multi-dimensional knapsack problem.
2018-02-12T09:29:45ZLizárraga Olivas, EveliaBlesa Aguilera, Maria JosepBlum, ChristianBoth, Construct, Merge, Solve and Adapt (CMSA) and Large Neighborhood Search (LNS), are hybrid algorithms that are based on iteratively solving sub-instances of the original problem instances, if possible, to optimality. This is done by reducing the search space of the tackled problem instance in algorithm-specific ways which differ from one technique to the other. In this paper we provide first experimental evidence for the intuition that, conditioned by the way in which the search space is reduced, LNS should generally work better than CMSA in the context of problems in which solutions are rather large, and the opposite is the case for problems in which solutions are rather small. The size of a solution is hereby measured by the number of components of which the solution is composed, in comparison to the total number of solution components. Experiments are conducted in the context of the multi-dimensional knapsack problem.A hybrid evolutionary algorithm based on solution merging for the longest arc-preserving common subsequence problem
http://hdl.handle.net/2117/114020
A hybrid evolutionary algorithm based on solution merging for the longest arc-preserving common subsequence problem
Blum, Christian; Blesa Aguilera, Maria Josep
The longest arc-preserving common subsequence problem is an NP-hard combinatorial optimization problem from the field of computational biology. This problem finds applications, in particular, in the comparison of art-annotated ribonucleic acid (RNA) sequences. In this work we propose a simple, hybrid evolutionary algorithm to tackle this problem. The most important feature of this algorithm concerns a crossover operator based on solution merging. In solution merging, two or more solutions to the problem are merged, and an exact technique is used to find the best solution within this union. It is experimentally shown that the proposed algorithm outperforms a heuristic from the literature.
2018-02-12T08:33:14ZBlum, ChristianBlesa Aguilera, Maria JosepThe longest arc-preserving common subsequence problem is an NP-hard combinatorial optimization problem from the field of computational biology. This problem finds applications, in particular, in the comparison of art-annotated ribonucleic acid (RNA) sequences. In this work we propose a simple, hybrid evolutionary algorithm to tackle this problem. The most important feature of this algorithm concerns a crossover operator based on solution merging. In solution merging, two or more solutions to the problem are merged, and an exact technique is used to find the best solution within this union. It is experimentally shown that the proposed algorithm outperforms a heuristic from the literature.An angel-daemon approach to assess the uncertainty in the power of a collectivity to act
http://hdl.handle.net/2117/114018
An angel-daemon approach to assess the uncertainty in the power of a collectivity to act
Fragnito, Giulia; Gabarró Vallès, Joaquim; Serna Iglesias, María José
We propose the use of the angel-daemon framework to assess the Coleman's power of a collectivity to act under uncertainty in weighted voting games.
In this framework uncertainty profiles describe the potential changes in the weights of a weighted game and fixes the spread of the weights' change. For each uncertainty profile a strategic angel-daemon game can be considered. This game has two selfish players, the angel and the daemon, the angel selects its action as to maximize the effect on the measure under consideration while daemon acts oppositely.
Players angel and daemon give a balance between the best and the worst. The angel-daemon games associated to the Coleman's power are zero-sum games and therefore the expected utilities of all the Nash equilibria
are the same. In this way we can asses the Coleman's power under uncertainty. Besides introducing the framework for this particular setting we analyse basic properties and make some computational complexity considerations. We provide several examples based in the evolution of the voting rules of the EU Council of Ministers.
The final publication is available at link.springer.com
2018-02-12T08:02:40ZFragnito, GiuliaGabarró Vallès, JoaquimSerna Iglesias, María JoséWe propose the use of the angel-daemon framework to assess the Coleman's power of a collectivity to act under uncertainty in weighted voting games.
In this framework uncertainty profiles describe the potential changes in the weights of a weighted game and fixes the spread of the weights' change. For each uncertainty profile a strategic angel-daemon game can be considered. This game has two selfish players, the angel and the daemon, the angel selects its action as to maximize the effect on the measure under consideration while daemon acts oppositely.
Players angel and daemon give a balance between the best and the worst. The angel-daemon games associated to the Coleman's power are zero-sum games and therefore the expected utilities of all the Nash equilibria
are the same. In this way we can asses the Coleman's power under uncertainty. Besides introducing the framework for this particular setting we analyse basic properties and make some computational complexity considerations. We provide several examples based in the evolution of the voting rules of the EU Council of Ministers.Parsing logical grammar: CatLog3
http://hdl.handle.net/2117/113964
Parsing logical grammar: CatLog3
Morrill, Glyn
CatLog3 is a Prolog parser/theorem-prover for (type) logical (categorial) grammar. In such logical grammar, grammar is reduced to logic: a string of words is grammatical if and only if an associated logical statement is a theorem. CalLog3 implements a logic extending displacement calculus, a sublinear fragment including as primitive connectives the continuous (Lambek) and discontinuous wrapping connectives of the displacement calculus, additives, 1st order quantifiers, normal modalities, bracket modalities and subexponentials. In this paper we survey how CatLog3 is implemented on the principles of Andreoli’s focusing and a generalisation of van Benthem’s
count-invariance.
2018-02-09T10:11:49ZMorrill, GlynCatLog3 is a Prolog parser/theorem-prover for (type) logical (categorial) grammar. In such logical grammar, grammar is reduced to logic: a string of words is grammatical if and only if an associated logical statement is a theorem. CalLog3 implements a logic extending displacement calculus, a sublinear fragment including as primitive connectives the continuous (Lambek) and discontinuous wrapping connectives of the displacement calculus, additives, 1st order quantifiers, normal modalities, bracket modalities and subexponentials. In this paper we survey how CatLog3 is implemented on the principles of Andreoli’s focusing and a generalisation of van Benthem’s
count-invariance.A polynomial-time algorithm for the Lambek calculus with brackets of bounded order
http://hdl.handle.net/2117/113963
A polynomial-time algorithm for the Lambek calculus with brackets of bounded order
Kanovich, Max; Kuznetsov, Stepan; Morrill, Glyn; Scedrov, Andre
Lambek calculus is a logical foundation of categorial grammar, a linguistic paradigm of grammar as logic and parsing as deduction. Pentus (2010) gave a polynomial-time algorithm for determining
provability of bounded depth formulas in L*, the Lambek calculus with empty antecedents allowed. Pentus’ algorithm is based on tabularisation of proof nets. Lambek calculus with brackets is a conservative extension of Lambek calculus with bracket modalities, suitable for the modeling of syntactical domains. In this paper we give an algorithm for provability in Lb*, the Lambek calculus with brackets allowing empty antecedents. Our algorithm runs in polynomial time when both the formula depth and the bracket nesting depth are bounded. It combines a Pentus-style tabularisation of proof nets with an automata-theoretic treatment of bracketing.
2018-02-09T09:57:17ZKanovich, MaxKuznetsov, StepanMorrill, GlynScedrov, AndreLambek calculus is a logical foundation of categorial grammar, a linguistic paradigm of grammar as logic and parsing as deduction. Pentus (2010) gave a polynomial-time algorithm for determining
provability of bounded depth formulas in L*, the Lambek calculus with empty antecedents allowed. Pentus’ algorithm is based on tabularisation of proof nets. Lambek calculus with brackets is a conservative extension of Lambek calculus with bracket modalities, suitable for the modeling of syntactical domains. In this paper we give an algorithm for provability in Lb*, the Lambek calculus with brackets allowing empty antecedents. Our algorithm runs in polynomial time when both the formula depth and the bracket nesting depth are bounded. It combines a Pentus-style tabularisation of proof nets with an automata-theoretic treatment of bracketing.