LARCA - Laboratori d'Algorísmia Relacional, Complexitat i Aprenentatge
http://hdl.handle.net/2117/3486
Fri, 06 May 2016 05:52:21 GMT2016-05-06T05:52:21ZEstimaciones de promedios en análisis
http://hdl.handle.net/2117/86042
Estimaciones de promedios en análisis
Boza Rocho, Santiago; Soria de Diego, Javier
Existen en Análisis una serie de resultados clásicos en los que el cálculo de promedios juega un papel relevante, como los métodos generalizados de convergencia, el teorema Fundamental del Cálculo o el tratamiento digital de imágenes. Para entender mejor estas ideas, desarrollaremos brevemente algunas de las técnicas más útiles que permiten obtener buenas estimaciones de dichos promedios. En particular, mencionaremos las desigualdades de Hardy, propiedades de la convolución, operadores maximales, aproximaciones de la identidad, lemas de cubrimiento, reordenamientos decrecientes, etc. Al final del artículo presentaremos también algunos problemas interesantes, todavía sin resolver.
Thu, 21 Apr 2016 10:18:15 GMThttp://hdl.handle.net/2117/860422016-04-21T10:18:15ZBoza Rocho, SantiagoSoria de Diego, JavierExisten en Análisis una serie de resultados clásicos en los que el cálculo de promedios juega un papel relevante, como los métodos generalizados de convergencia, el teorema Fundamental del Cálculo o el tratamiento digital de imágenes. Para entender mejor estas ideas, desarrollaremos brevemente algunas de las técnicas más útiles que permiten obtener buenas estimaciones de dichos promedios. En particular, mencionaremos las desigualdades de Hardy, propiedades de la convolución, operadores maximales, aproximaciones de la identidad, lemas de cubrimiento, reordenamientos decrecientes, etc. Al final del artículo presentaremos también algunos problemas interesantes, todavía sin resolver.Tractable clones of polynomials over semigroups
http://hdl.handle.net/2117/85850
Tractable clones of polynomials over semigroups
Dalmau, Víctor; Gavaldà Mestre, Ricard; Tesson, Pascal; Thérien, Denis
We contribute to the algebraic study of the complexity of constraint satisfaction problems. We give a new sufficient condition on a set of relations R over a domain S for the tractability of CSP(R): if S is a block-group (a particular class of semigroups) of exponent w and R is a set of relations over S preserved by the operation defined by the polynomial f(x,y,z) = xy^(w-1)z over S, then CSP(R) is tractable. This theorem strictly improves on results of Feder and Vardi and Bulatov et al. and we demonstrate it by reproving an upper bound of Klima et al. We also investigate systematically the tractability of CSP(R) when R is a set of relations closed under operations that are all expressible as polynomials over a finite semigroup S. In particular, if S is a nilpotent group, we show that CSP(R) is tractable iff one of these polynomials defines a Malt'sev operation, and conjecture that this holds for all groups.
Tue, 19 Apr 2016 07:00:57 GMThttp://hdl.handle.net/2117/858502016-04-19T07:00:57ZDalmau, VíctorGavaldà Mestre, RicardTesson, PascalThérien, DenisWe contribute to the algebraic study of the complexity of constraint satisfaction problems. We give a new sufficient condition on a set of relations R over a domain S for the tractability of CSP(R): if S is a block-group (a particular class of semigroups) of exponent w and R is a set of relations over S preserved by the operation defined by the polynomial f(x,y,z) = xy^(w-1)z over S, then CSP(R) is tractable. This theorem strictly improves on results of Feder and Vardi and Bulatov et al. and we demonstrate it by reproving an upper bound of Klima et al. We also investigate systematically the tractability of CSP(R) when R is a set of relations closed under operations that are all expressible as polynomials over a finite semigroup S. In particular, if S is a nilpotent group, we show that CSP(R) is tractable iff one of these polynomials defines a Malt'sev operation, and conjecture that this holds for all groups.Liberating language research from dogmas of the 20th century
http://hdl.handle.net/2117/85273
Liberating language research from dogmas of the 20th century
Ferrer Cancho, Ramon; Gómez Rodríguez, Carlos
A commentary on the article “Large-scale evidence of dependency length
minimization in 37 languages” by Futrell, Mahowald & Gibson (PNAS 2015 112 (33) 10336-10341).
Wed, 06 Apr 2016 09:32:25 GMThttp://hdl.handle.net/2117/852732016-04-06T09:32:25ZFerrer Cancho, RamonGómez Rodríguez, CarlosA commentary on the article “Large-scale evidence of dependency length
minimization in 37 languages” by Futrell, Mahowald & Gibson (PNAS 2015 112 (33) 10336-10341).GeoSRS: a hybrid social recommender system for geolocated data
http://hdl.handle.net/2117/84070
GeoSRS: a hybrid social recommender system for geolocated data
Capdevila Pujol, Joan; Arias Vicente, Marta; Arratia Quesada, Argimiro Alejandro
All right sreserved. We present GeoSRS, a hybrid recommender system for a popular location-based social network (LBSN), in which users are able to write short reviews on the places of interest they visit. Using state-of-the-art text mining techniques, our system recommends locations to users using as source the whole set of text reviews in addition to their geographical location. To evaluate our system, we have collected our own data sets by crawling the social network Foursquare. To do this efficiently, we propose the use of a parallel version of the Quadtree technique, which may be applicable to crawling/exploring other spatially distributed sources. Finally, we study the performance of GeoSRS on our collected data set and conclude that by combining sentiment analysis and text modeling, GeoSRS generates more accurate recommendations. The performance of the system improves as more reviews are available, which further motivates the use of large-scale crawling techniques such as the Quadtree.
Wed, 09 Mar 2016 14:36:56 GMThttp://hdl.handle.net/2117/840702016-03-09T14:36:56ZCapdevila Pujol, JoanArias Vicente, MartaArratia Quesada, Argimiro AlejandroAll right sreserved. We present GeoSRS, a hybrid recommender system for a popular location-based social network (LBSN), in which users are able to write short reviews on the places of interest they visit. Using state-of-the-art text mining techniques, our system recommends locations to users using as source the whole set of text reviews in addition to their geographical location. To evaluate our system, we have collected our own data sets by crawling the social network Foursquare. To do this efficiently, we propose the use of a parallel version of the Quadtree technique, which may be applicable to crawling/exploring other spatially distributed sources. Finally, we study the performance of GeoSRS on our collected data set and conclude that by combining sentiment analysis and text modeling, GeoSRS generates more accurate recommendations. The performance of the system improves as more reviews are available, which further motivates the use of large-scale crawling techniques such as the Quadtree.Quantitative redundancy in partial implications
http://hdl.handle.net/2117/83945
Quantitative redundancy in partial implications
Balcázar Navarro, José Luis
We survey the different properties of an intuitive notion of redundancy, as a function of the precise semantics given to the notion of partial implication.
Tue, 08 Mar 2016 09:45:52 GMThttp://hdl.handle.net/2117/839452016-03-08T09:45:52ZBalcázar Navarro, José LuisWe survey the different properties of an intuitive notion of redundancy, as a function of the precise semantics given to the notion of partial implication.Computational coverage of TLG : the Montague test
http://hdl.handle.net/2117/83591
Computational coverage of TLG : the Montague test
Morrill, Glyn; Valentín Fernández Gallart, José Oriol
This paper reports on the empirical coverage of Type Logical Grammar (TLG) and on how it has been computer implemented. We analyse the Montague fragment computationally and we proffer this task as a challenge to computational grammar: the Montague Test
Tue, 01 Mar 2016 11:01:04 GMThttp://hdl.handle.net/2117/835912016-03-01T11:01:04ZMorrill, GlynValentín Fernández Gallart, José OriolThis paper reports on the empirical coverage of Type Logical Grammar (TLG) and on how it has been computer implemented. We analyse the Montague fragment computationally and we proffer this task as a challenge to computational grammar: the Montague TestAn efficient closed frequent itemset miner for the MOA stream mining system
http://hdl.handle.net/2117/82987
An efficient closed frequent itemset miner for the MOA stream mining system
Quadrana, Massimo; Bifet Figuerol, Albert Carles; Gavaldà Mestre, Ricard
Mining itemsets is a central task in data mining, both in the batch and the streaming paradigms. While robust, efficient, and well-tested implementations exist for batch mining, hardly any publicly available equivalent exists for the streaming scenario. The lack of an efficient, usable tool for the task hinders its use by practitioners and makes it difficult to assess new research in the area. To alleviate this situation, we review the algorithms described in the literature, and implement and evaluate the IncMine algorithm by Cheng, Ke and Ng [J. Intell. Inf. Syst. 31(3) (2008), 191–215] for mining frequent closed itemsets from data streams. Our implementation works on top of the MOA (Massive Online Analysis) stream mining framework to ease its use and integration with other stream mining tasks. We provide a PAC-style rigorous analysis of the quality of the output of IncMine as a function of its parameters; this type of analysis is rare in pattern mining algorithms. As a by-product, the analysis shows how one of the user-provided parameters in the original description can be removed entirely while retaining the performance guarantees. Finally, we experimentally confirm both on synthetic and real data the excellent performance of the algorithm, as reported in the original paper, and its ability to handle concept drift.
Tue, 16 Feb 2016 08:02:25 GMThttp://hdl.handle.net/2117/829872016-02-16T08:02:25ZQuadrana, MassimoBifet Figuerol, Albert CarlesGavaldà Mestre, RicardMining itemsets is a central task in data mining, both in the batch and the streaming paradigms. While robust, efficient, and well-tested implementations exist for batch mining, hardly any publicly available equivalent exists for the streaming scenario. The lack of an efficient, usable tool for the task hinders its use by practitioners and makes it difficult to assess new research in the area. To alleviate this situation, we review the algorithms described in the literature, and implement and evaluate the IncMine algorithm by Cheng, Ke and Ng [J. Intell. Inf. Syst. 31(3) (2008), 191–215] for mining frequent closed itemsets from data streams. Our implementation works on top of the MOA (Massive Online Analysis) stream mining framework to ease its use and integration with other stream mining tasks. We provide a PAC-style rigorous analysis of the quality of the output of IncMine as a function of its parameters; this type of analysis is rare in pattern mining algorithms. As a by-product, the analysis shows how one of the user-provided parameters in the original description can be removed entirely while retaining the performance guarantees. Finally, we experimentally confirm both on synthetic and real data the excellent performance of the algorithm, as reported in the original paper, and its ability to handle concept drift.Computational coverage of TLG: displacement
http://hdl.handle.net/2117/82818
Computational coverage of TLG: displacement
Morrill, Glyn; Valentín Fernández Gallart, José Oriol
This paper reports on the coverage of TLG of Morrill (1994) and Moortgat (1997), and on how it has been computer implemented. We computer-analyse examples of displacement: discontinuous idioms, quantification, (medial) relativisation, VP ellipsis, (medial) pied piping, appositive relativisation, parentheticals, gapping, comparative
subdeletion, and reflexivisation, and, in the appendix, Dutch verb raising and crossserial dependency.
Thu, 11 Feb 2016 09:25:44 GMThttp://hdl.handle.net/2117/828182016-02-11T09:25:44ZMorrill, GlynValentín Fernández Gallart, José OriolThis paper reports on the coverage of TLG of Morrill (1994) and Moortgat (1997), and on how it has been computer implemented. We computer-analyse examples of displacement: discontinuous idioms, quantification, (medial) relativisation, VP ellipsis, (medial) pied piping, appositive relativisation, parentheticals, gapping, comparative
subdeletion, and reflexivisation, and, in the appendix, Dutch verb raising and crossserial dependency.Computational coverage of TLG: nonlinearity
http://hdl.handle.net/2117/82813
Computational coverage of TLG: nonlinearity
Morrill, Glyn; Valentín Fernández Gallart, José Oriol
We study nonlinear connectives (exponentials) in the context of Type Logical Grammar (TLG). We devise four conservative extensions of the displacement calculus with brackets, Db!, Db!?, Db!b and Db!b?r which contain the universal and existential exponential modalities of linear logic (LL). These modalities do not exhibit the same structural properties as in LL, which in TLG are especially adapted for linguistic purposes. The universal modality ! for TLG allows only the commutative and contraction rules, but not weakening, whereas the existential modality ? allows the so-called (intuitionistic) Mingle rule, which derives a restricted version of weakening. We provide a Curry-Howard labelling for both exponential connectives. As it turns out, controlled contraction by ! gives a way to account for the so-called parasitic gaps, and controlled Mingle ? iteration, in particular iterated coordination.
Finally, the four calculi are proved to be Cut-Free, and decidability is proved for a linguistically suffcient special case of Db!b?r (and hence
Db!b).
Thu, 11 Feb 2016 09:02:19 GMThttp://hdl.handle.net/2117/828132016-02-11T09:02:19ZMorrill, GlynValentín Fernández Gallart, José OriolWe study nonlinear connectives (exponentials) in the context of Type Logical Grammar (TLG). We devise four conservative extensions of the displacement calculus with brackets, Db!, Db!?, Db!b and Db!b?r which contain the universal and existential exponential modalities of linear logic (LL). These modalities do not exhibit the same structural properties as in LL, which in TLG are especially adapted for linguistic purposes. The universal modality ! for TLG allows only the commutative and contraction rules, but not weakening, whereas the existential modality ? allows the so-called (intuitionistic) Mingle rule, which derives a restricted version of weakening. We provide a Curry-Howard labelling for both exponential connectives. As it turns out, controlled contraction by ! gives a way to account for the so-called parasitic gaps, and controlled Mingle ? iteration, in particular iterated coordination.
Finally, the four calculi are proved to be Cut-Free, and decidability is proved for a linguistically suffcient special case of Db!b?r (and hence
Db!b).Characterizing chronic disease and polymedication prescription patterns from electronic health records
http://hdl.handle.net/2117/82778
Characterizing chronic disease and polymedication prescription patterns from electronic health records
Zamora, Martí; Baradad, Manel; Amado, Ester; Cordomí, Sílvia; Limón, Esther; Ribera, Juliana; Arias Vicente, Marta; Gavaldà Mestre, Ricard
Population aging in developed countries brings an increased prevalence of chronic disease and of polymedication-patients with several prescribed types of medication. Attention to chronic, polymedicated patients is a priority for its high cost and the associated risks, and tools for analyzing, understanding, and managing this reality are becoming necessary. We describe a prototype of a system for discovering, analyzing, and visualizing the co-occurrence of diagnostics, interventions, and medication prescriptions in a large patient database. The final tool is intended to be used both by health managers and planners and for primary care clinicians in direct contact with patients (for example for detecting unusual disease patterns and incorrect or missing medication). At the core of the analysis module there is a representation of diagnostics and medications as a hypergraph, and the most crucial functionalities rely on hypergraph transversal/variants of association rule discovery methods, with particular emphasis on discovering surprising or alarming combinations. The test database comes from the primary care system in the area of Barcelona for 2013, with over 1.6 million potential patients and almost 20 million diagnostics and prescriptions.
Wed, 10 Feb 2016 13:17:39 GMThttp://hdl.handle.net/2117/827782016-02-10T13:17:39ZZamora, MartíBaradad, ManelAmado, EsterCordomí, SílviaLimón, EstherRibera, JulianaArias Vicente, MartaGavaldà Mestre, RicardPopulation aging in developed countries brings an increased prevalence of chronic disease and of polymedication-patients with several prescribed types of medication. Attention to chronic, polymedicated patients is a priority for its high cost and the associated risks, and tools for analyzing, understanding, and managing this reality are becoming necessary. We describe a prototype of a system for discovering, analyzing, and visualizing the co-occurrence of diagnostics, interventions, and medication prescriptions in a large patient database. The final tool is intended to be used both by health managers and planners and for primary care clinicians in direct contact with patients (for example for detecting unusual disease patterns and incorrect or missing medication). At the core of the analysis module there is a representation of diagnostics and medications as a hypergraph, and the most crucial functionalities rely on hypergraph transversal/variants of association rule discovery methods, with particular emphasis on discovering surprising or alarming combinations. The test database comes from the primary care system in the area of Barcelona for 2013, with over 1.6 million potential patients and almost 20 million diagnostics and prescriptions.