DSpace Collection:
http://hdl.handle.net/2117/3094
2014-04-21T10:11:57ZOn the proper intervalization of colored caterpillar trees
http://hdl.handle.net/2117/12953
Title: On the proper intervalization of colored caterpillar trees
Authors: Álvarez Faura, M. del Carme; Serna Iglesias, María José
Abstract: This paper studies the computational complexity of the Proper interval colored graph problem (picg), when the input graph is a colored caterpillar, parameterized by hair length. In order prove our result we establish a close relationship between the picg and a graph layout problem the Proper colored layout problem (pclp). We show a dichotomy: the picg and the pclp are NP-complete for colored caterpillars of hair length ≥ 2, while both problems are in P for colored caterpillars of hair length < 2. For the hardness results we provide a reduction from the Multiprocessor Scheduling problem, while the polynomial time results follow from a characterization in terms of forbidden subgraphs.2011-07-13T09:48:20ZSensor field: a computational model
http://hdl.handle.net/2117/12934
Title: Sensor field: a computational model
Authors: Álvarez Faura, M. del Carme; Duch Brown, Amalia; Gabarró Vallès, Joaquim; Serna Iglesias, María José
Abstract: We introduce a formal model of computation for networks of tiny artifacts, the static synchronous sensor field model (SSSF) which
considers that the devices communicate through a fixed communication graph and interact with the environment through input/output data streams. We analyze the performance of SSSFs solving two sensing problems the Average Monitoring and the Alerting problems. For constant memory SSSFs we show that the set of recognized languages is contained in DSPACE(n+m) where n is the number of nodes of the communication graph and m its number of edges. Finally we explore the capabilities of SSSFs having sensing and additional non-sensing constant memory devices.2011-07-12T10:23:04ZTheoretical aspects of graph models for MANETS
http://hdl.handle.net/2117/9758
Title: Theoretical aspects of graph models for MANETS
Authors: Díaz Cort, Josep; Dieter Wilhelm, Mitsche; Santi, Paolo
Abstract: We survey the main theoretical aspects of models for Mobile Ad
Hoc Networks (MANETs). We present theoretical characterizations of mobile
network structural properties, di erent dynamic graph models of MANETs,
and nally we give detailed summaries of a few selected articles. In particular,
we focus on articles dealing with connectivity of mobile networks, and on articles
which show that mobility can be used to propagate information between
nodes of the network while at the same time maintaining small transmission
distances, and thus saving energy.2010-10-18T10:04:10ZMaximum tolerance and maximum greatest tolerance
http://hdl.handle.net/2117/9550
Title: Maximum tolerance and maximum greatest tolerance
Authors: Freixas Bosch, Josep; Molinero Albareda, Xavier
Abstract: An important consideration when applying neural networks is the sensitivity
to weights and threshold in strict separating systems representing a
linearly separable function. Two parameters have been introduced to measure
the relative errors in weights and threshold of strict separating systems:
the tolerance and the greatest tolerance. Given an arbitrary separating system
we study which is the equivalent separating system that provides maximum
tolerance or/and maximum greatest tolerance.2010-10-07T14:19:24ZWeighted games without a unique minimal representation in integers
http://hdl.handle.net/2117/9295
Title: Weighted games without a unique minimal representation in integers
Authors: Freixas Bosch, Josep; Molinero Albareda, Xavier
Abstract: Recerca de jocs amb mínim número de jugadors sense representacions enteres mínimes o mínimes normalitzades
Description: Isbell in 1959 was the first to find a weighted game without a minimum integer realization
in which the affected players do not play a symmetric role in the game. His example has 12
players is a weighted decisive game, i.e. a weighted game for which a coalition wins iff its
complement loses. The goal of this paper is to provide a procedure for weighted games that
allows finding out what is the minimum number of players needed to get a weighted game
without a minimum integer weighted representation in which the affected players do not play
a symmetric role in the game. We prove, by means of an algorithm, that the minimum number
of voters required is 9.2010-10-04T17:23:00ZOn the complexity of problems on simple games
http://hdl.handle.net/2117/8956
Title: On the complexity of problems on simple games
Authors: Freixas Bosch, Josep; Molinero Albareda, Xavier; Olsen, Martin; Serna Iglesias, María José
Abstract: Simple games cover voting systems in which a single alternative, such
as a bill or an amendment, is pitted against the status quo. A simple game
or a yes–no voting system is a set of rules that specifies exactly which
collections of “yea” votes yield passage of the issue at hand, each of these
collections of “yea” voters forms a winning coalition. We are interested in
performing a complexity analysis on problems defined on such families of
games. This analysis as usual depends on the game representation used as
input. We consider four natural explicit representations: winning, losing,
minimal winning, and maximal losing. We first analyze the complexity of
testing whether a game is simple and testing whether a game is weighted.
We show that, for the four types of representations, both problems can be
solved in polynomial time. Finally, we provide results on the complexity
of testing whether a simple game or a weighted game is of a special type.
We analyze strongness, properness, decisiveness and homogeneity, which
are desirable properties to be fulfilled for a simple game. We finalize
with some considerations on the possibility of representing a game in a
more succinct representation showing a natural representation in which
the recognition problem is hard.2010-09-17T15:45:57ZA Fibonacci sequence for linear structures with two types of components
http://hdl.handle.net/2117/7703
Title: A Fibonacci sequence for linear structures with two types of components
Authors: Freixas Bosch, Josep; Molinero Albareda, Xavier; Roura Ferret, Salvador
Abstract: We investigate binary voting systems with two types of voters and a hierarchy among
the members in each type, so that members in one class have more influence or importance
than members in the other class. The purpose of this paper is to count, up to isomorphism,
the number of these voting systems for an arbitrary number of voters. We obtain a closed formula for the number of these systems, this formula follows a Fibonacci sequence with a smooth polynomial variation on the number of voters.2010-06-16T15:23:20Z