Ponències/Comunicacions de congressos
http://hdl.handle.net/2117/3095
Tue, 28 Mar 2017 02:31:04 GMT2017-03-28T02:31:04ZFraud detection in energy consumption: a supervised approach
http://hdl.handle.net/2117/101913
Fraud detection in energy consumption: a supervised approach
Coma Puig, Bernat; Carmona Vargas, Josep; Gavaldà Mestre, Ricard; Alcoverro, Santiago; Martín, Victor
Data from utility meters (gas, electricity, water) is a rich source of information for distribution companies, beyond billing. In this paper we present a supervised technique, which primarily but not only feeds on meter information, to detect meter anomalies and customer fraudulent behavior (meter tampering). Our system detects anomalous meter readings on the basis of models built using machine learning techniques on past data. Unlike most previous work, it can incrementally incorporate the result of field checks to grow the database of fraud and non-fraud patterns, therefore increasing model precision over time and potentially adapting to emerging fraud patterns. The full system has been developed with a company providing electricity and gas and already used to carry out several field checks, with large improvements in fraud detection over the previous checks which used simpler techniques.
Fri, 03 Mar 2017 12:09:34 GMThttp://hdl.handle.net/2117/1019132017-03-03T12:09:34ZComa Puig, BernatCarmona Vargas, JosepGavaldà Mestre, RicardAlcoverro, SantiagoMartín, VictorData from utility meters (gas, electricity, water) is a rich source of information for distribution companies, beyond billing. In this paper we present a supervised technique, which primarily but not only feeds on meter information, to detect meter anomalies and customer fraudulent behavior (meter tampering). Our system detects anomalous meter readings on the basis of models built using machine learning techniques on past data. Unlike most previous work, it can incrementally incorporate the result of field checks to grow the database of fraud and non-fraud patterns, therefore increasing model precision over time and potentially adapting to emerging fraud patterns. The full system has been developed with a company providing electricity and gas and already used to carry out several field checks, with large improvements in fraud detection over the previous checks which used simpler techniques.Partial match queries in relaxed K-dt trees
http://hdl.handle.net/2117/101520
Partial match queries in relaxed K-dt trees
Duch Brown, Amalia; Lau Laynes-Lozada, Gustavo Salvador
The study of partial match queries on random hierarchical multidimensional data structures dates back to Ph. Flajolet and C. Puech’s 1986 seminal paper on partial match retrieval. It was not until recently that fixed (as opposed to random) partial match queries were studied for random relaxed K-d trees, random standard K-d trees, and random 2-dimensional quad trees. Based on those results it seemed
natural to classify the general form of the cost of fixed partial match queries into two families: that of either random hierarchical structures or perfectly balanced structures, as conjectured by Duch, Lau and Martínez (On the Cost of Fixed Partial Queries in K-d trees Algorithmica, 75(4):684–723, 2016). Here we show that the conjecture just mentioned does not hold by introducing relaxed K-dt trees and providing the average-case analysis for random partial match queries as well as some advances on the average-case analysis for fixed partial match queries on them. In fact this cost –for fixed partial match queries– does not follow the conjectured forms.
Fri, 24 Feb 2017 10:27:25 GMThttp://hdl.handle.net/2117/1015202017-02-24T10:27:25ZDuch Brown, AmaliaLau Laynes-Lozada, Gustavo SalvadorThe study of partial match queries on random hierarchical multidimensional data structures dates back to Ph. Flajolet and C. Puech’s 1986 seminal paper on partial match retrieval. It was not until recently that fixed (as opposed to random) partial match queries were studied for random relaxed K-d trees, random standard K-d trees, and random 2-dimensional quad trees. Based on those results it seemed
natural to classify the general form of the cost of fixed partial match queries into two families: that of either random hierarchical structures or perfectly balanced structures, as conjectured by Duch, Lau and Martínez (On the Cost of Fixed Partial Queries in K-d trees Algorithmica, 75(4):684–723, 2016). Here we show that the conjecture just mentioned does not hold by introducing relaxed K-dt trees and providing the average-case analysis for random partial match queries as well as some advances on the average-case analysis for fixed partial match queries on them. In fact this cost –for fixed partial match queries– does not follow the conjectured forms.Mining structured Petri nets for the visualization of process behavior
http://hdl.handle.net/2117/100797
Mining structured Petri nets for the visualization of process behavior
San Pedro Martín, Javier de; Cortadella Fortuny, Jordi
Visualization is essential for understanding the models obtained by process mining. Clear and efficient visual representations make the embedded information more accessible and analyzable. This work presents a novel approach for generating process models with structural properties that induce visually friendly layouts. Rather than generating a single model that captures all behaviors, a set of Petri net models is delivered, each one covering a subset of traces of the log. The models are mined by extracting slices of labelled transition systems with specific properties from the complete state space produced by the process logs. In most cases, few Petri nets are sufficient to cover a significant part of the behavior produced by the log.
Fri, 10 Feb 2017 08:35:24 GMThttp://hdl.handle.net/2117/1007972017-02-10T08:35:24ZSan Pedro Martín, Javier deCortadella Fortuny, JordiVisualization is essential for understanding the models obtained by process mining. Clear and efficient visual representations make the embedded information more accessible and analyzable. This work presents a novel approach for generating process models with structural properties that induce visually friendly layouts. Rather than generating a single model that captures all behaviors, a set of Petri net models is delivered, each one covering a subset of traces of the log. The models are mined by extracting slices of labelled transition systems with specific properties from the complete state space produced by the process logs. In most cases, few Petri nets are sufficient to cover a significant part of the behavior produced by the log.Comparing MapReduce and pipeline implementations for counting triangles
http://hdl.handle.net/2117/100579
Comparing MapReduce and pipeline implementations for counting triangles
Pasarella Sánchez, Ana Edelmira; Vidal Serodio, Maria Esther; Zoltan, Cristina
A generalized method to define the Divide & Conquer paradigm in order to have processors acting on its own data and scheduled in a
parallel fashion. MapReduce is a programming model that follows this paradigm, and allows for the definition of efficient solutions by both decomposing a problem into steps on subsets of the input data
and combining the results of each step to produce final results. Albeit used for the implementation of a wide variety of computational problems, MapReduce performance can be negatively affected
whenever the replication factor grows or the size of the input is larger than the resources available at each processor. In this paper we show an alternative approach to implement the Divide & Conquer
paradigm, named pipeline. The main features of pipeline are illustrated on a parallel implementation of the well-known problem of counting triangles in a graph. This problem is especially interesting either when the input graph does not fit in memory or is dynamically generated. To evaluate the properties of pipeline, a dynamic pipeline of processes and an ad-hoc version of MapReduce are implemented in the language Go, exploiting its ability to deal with channels and spawned processes.
An empirical evaluation is conducted on graphs of different sizes and densities. Observed results suggest that pipeline allows for the implementation of an efficient solution of the problem of counting
triangles in a graph, particularly, in dense and large graphs, drastically reducing the execution time with respect to the MapReduce implementation.
Mon, 06 Feb 2017 08:48:11 GMThttp://hdl.handle.net/2117/1005792017-02-06T08:48:11ZPasarella Sánchez, Ana EdelmiraVidal Serodio, Maria EstherZoltan, CristinaA generalized method to define the Divide & Conquer paradigm in order to have processors acting on its own data and scheduled in a
parallel fashion. MapReduce is a programming model that follows this paradigm, and allows for the definition of efficient solutions by both decomposing a problem into steps on subsets of the input data
and combining the results of each step to produce final results. Albeit used for the implementation of a wide variety of computational problems, MapReduce performance can be negatively affected
whenever the replication factor grows or the size of the input is larger than the resources available at each processor. In this paper we show an alternative approach to implement the Divide & Conquer
paradigm, named pipeline. The main features of pipeline are illustrated on a parallel implementation of the well-known problem of counting triangles in a graph. This problem is especially interesting either when the input graph does not fit in memory or is dynamically generated. To evaluate the properties of pipeline, a dynamic pipeline of processes and an ad-hoc version of MapReduce are implemented in the language Go, exploiting its ability to deal with channels and spawned processes.
An empirical evaluation is conducted on graphs of different sizes and densities. Observed results suggest that pipeline allows for the implementation of an efficient solution of the problem of counting
triangles in a graph, particularly, in dense and large graphs, drastically reducing the execution time with respect to the MapReduce implementation.A semantics of business configurations using symbolic graphs
http://hdl.handle.net/2117/100385
A semantics of business configurations using symbolic graphs
Mylonakis Pascual, Nicolás; Orejas Valdés, Fernando; Fiadeiro, José Luiz
In this paper we give graph-semantics to a fundamental part of the semantics of the service modeling language SRML: business configurations. To achieve this goal we use symbolic graph transformation systems. We formalize the semantics using this graph transformation system and illustrating it with a simple running example of a trip booking agent.
Tue, 31 Jan 2017 13:43:47 GMThttp://hdl.handle.net/2117/1003852017-01-31T13:43:47ZMylonakis Pascual, NicolásOrejas Valdés, FernandoFiadeiro, José LuizIn this paper we give graph-semantics to a fundamental part of the semantics of the service modeling language SRML: business configurations. To achieve this goal we use symbolic graph transformation systems. We formalize the semantics using this graph transformation system and illustrating it with a simple running example of a trip booking agent.Conditions for compatibility of components: The case of masters and slaves
http://hdl.handle.net/2117/100199
Conditions for compatibility of components: The case of masters and slaves
Beek, Maurice ter; Carmona Vargas, Josep; Kleijn, Jetty
We consider systems composed of reactive components that collaborate through synchronised execution of common actions. These multi-component systems are formally represented as team automata, a model that allows a wide spectrum of synchronisation policies to combine components into higher-level systems. We investigate the
correct-by-construction engineering of such systems of systems from the point of view of correct communications between the components (no message loss or deadlocks due to indefinite waiting). This leads to a proposal for a generic definition of compatibility of components relative to the adopted synchronisation policy. This definition appears
to be particularly appropriate for so-called master-slave synchronisations by which input actions (for `slaves') are driven
by output actions (from `masters').
Fri, 27 Jan 2017 12:09:50 GMThttp://hdl.handle.net/2117/1001992017-01-27T12:09:50ZBeek, Maurice terCarmona Vargas, JosepKleijn, JettyWe consider systems composed of reactive components that collaborate through synchronised execution of common actions. These multi-component systems are formally represented as team automata, a model that allows a wide spectrum of synchronisation policies to combine components into higher-level systems. We investigate the
correct-by-construction engineering of such systems of systems from the point of view of correct communications between the components (no message loss or deadlocks due to indefinite waiting). This leads to a proposal for a generic definition of compatibility of components relative to the adopted synchronisation policy. This definition appears
to be particularly appropriate for so-called master-slave synchronisations by which input actions (for `slaves') are driven
by output actions (from `masters').Non-homogenizable classes of finite structures
http://hdl.handle.net/2117/100189
Non-homogenizable classes of finite structures
Atserias, Albert; Torunczyk, Szymon Abram
Homogenization is a powerful way of taming a class of finite structures with several interesting applications in different areas, from Ramsey theory in combinatorics to constraint satisfaction problems (CSPs) in computer science, through (finite) model theory. A few sufficient conditions for a class of finite structures to allow homogenization are known, and here we provide a necessary condition. This lets us show that certain natural classes are not homogenizable: 1) the class of locally consistent systems of linear equations over the two-element field or any finite Abelian group, and 2) the class of finite structures that forbid homomorphisms from a specific MSO-definable class of structures of treewidth two. In combination with known results, the first example shows that, up to pp-interpretability, the CSPs that are solvable by local consistency methods are distinguished from the rest by the fact that their classes of locally consistent instances are homogenizable. The second example shows that, for MSO-definable classes of forbidden patterns, treewidth one versus two is the dividing line to homogenizability.
Fri, 27 Jan 2017 10:51:13 GMThttp://hdl.handle.net/2117/1001892017-01-27T10:51:13ZAtserias, AlbertTorunczyk, Szymon AbramHomogenization is a powerful way of taming a class of finite structures with several interesting applications in different areas, from Ramsey theory in combinatorics to constraint satisfaction problems (CSPs) in computer science, through (finite) model theory. A few sufficient conditions for a class of finite structures to allow homogenization are known, and here we provide a necessary condition. This lets us show that certain natural classes are not homogenizable: 1) the class of locally consistent systems of linear equations over the two-element field or any finite Abelian group, and 2) the class of finite structures that forbid homomorphisms from a specific MSO-definable class of structures of treewidth two. In combination with known results, the first example shows that, up to pp-interpretability, the CSPs that are solvable by local consistency methods are distinguished from the rest by the fact that their classes of locally consistent instances are homogenizable. The second example shows that, for MSO-definable classes of forbidden patterns, treewidth one versus two is the dividing line to homogenizability.A logic of graph conditions extended with paths
http://hdl.handle.net/2117/100161
A logic of graph conditions extended with paths
Navarro Gomez, Marisa; Orejas Valdés, Fernando; Pino Blanco, Elvira; Lambers, Leen
In this paper we tackle the problem of extending the logic of nested graph conditions with paths. This means, for instance, that we may state properties about the existence of paths between some given nodes. As a main contribution, a sound and complete tableau method is defined for reasoning about this kind of properties.
Fri, 27 Jan 2017 09:01:41 GMThttp://hdl.handle.net/2117/1001612017-01-27T09:01:41ZNavarro Gomez, MarisaOrejas Valdés, FernandoPino Blanco, ElviraLambers, LeenIn this paper we tackle the problem of extending the logic of nested graph conditions with paths. This means, for instance, that we may state properties about the existence of paths between some given nodes. As a main contribution, a sound and complete tableau method is defined for reasoning about this kind of properties.A logic of graph conditions extended with paths
http://hdl.handle.net/2117/100160
A logic of graph conditions extended with paths
Navarro Gomez, Marisa; Orejas Valdés, Fernando; Pino Blanco, Elvira; Lambers, Leen
In this paper we tackle the problem of extending the logic of nested graph conditions with paths. This means, for instance, that we may state properties about the existence of paths between some given nodes. As a main contribution, a sound and complete tableau method is defined for reasoning about this kind of properties.
Fri, 27 Jan 2017 08:56:31 GMThttp://hdl.handle.net/2117/1001602017-01-27T08:56:31ZNavarro Gomez, MarisaOrejas Valdés, FernandoPino Blanco, ElviraLambers, LeenIn this paper we tackle the problem of extending the logic of nested graph conditions with paths. This means, for instance, that we may state properties about the existence of paths between some given nodes. As a main contribution, a sound and complete tableau method is defined for reasoning about this kind of properties.Specification mining for asynchronous controllers
http://hdl.handle.net/2117/99949
Specification mining for asynchronous controllers
San Pedro Martín, Javier de; Bourgeat, Thomas; Cortadella Fortuny, Jordi
The paper presents a first effort at exploring a novel area in the domain of asynchronous controllers: specification mining. Rather than synthesizing circuits from specifications, we aim at doing reverse engineering, i.e., discovering safe specifications from the circuits that preserve a set of pre-defined behavioral properties (e.g., hazard freeness). The specifications are discovered without any previous knowledge of the behavior of the circuit environment.
This area may open new opportunities for re-synthesis and verification of asynchronous controllers. The effectiveness of the proposed approach is demonstrated by mining concurrent specifications (Signal Transition Graphs) from multiple implementations of 4-phase handshake controllers and some controllers with choice.
Tue, 24 Jan 2017 13:19:10 GMThttp://hdl.handle.net/2117/999492017-01-24T13:19:10ZSan Pedro Martín, Javier deBourgeat, ThomasCortadella Fortuny, JordiThe paper presents a first effort at exploring a novel area in the domain of asynchronous controllers: specification mining. Rather than synthesizing circuits from specifications, we aim at doing reverse engineering, i.e., discovering safe specifications from the circuits that preserve a set of pre-defined behavioral properties (e.g., hazard freeness). The specifications are discovered without any previous knowledge of the behavior of the circuit environment.
This area may open new opportunities for re-synthesis and verification of asynchronous controllers. The effectiveness of the proposed approach is demonstrated by mining concurrent specifications (Signal Transition Graphs) from multiple implementations of 4-phase handshake controllers and some controllers with choice.