DSpace Community:
http://hdl.handle.net/2117/3178
2014-08-23T05:34:27ZSimulation of cable dynamics for moored ocean platforms: modeling aids design of large, underwater power cable
http://hdl.handle.net/2117/23616
Title: Simulation of cable dynamics for moored ocean platforms: modeling aids design of large, underwater power cable
Authors: Prat Farran, Joana d'Arc; Zaragoza Monroig, M. Luisa; Río Fernandez, Joaquín del2014-07-25T10:56:15ZPerfect edge-magic graphs
http://hdl.handle.net/2117/22939
Title: Perfect edge-magic graphs
Authors: López Masip, Susana Clara; Muntaner Batle, Francesc Antoni; Rius Font, Miquel
Abstract: The study of the possible valences for edge-magic labelings of graphs has motivated us to introduce the concept of perfect edge-magic graphs. Intuitively speaking, an edge-magic graph is perfect edge-magic if all possible theoretical valences occur. In particular, we prove that for each integer m > 0, that is the power of an odd prime, and for each natural number n, the crown product C-m circle dot (K-n) over bar is perfect edge-magic. Related results are also provided concerning other families of unicyclic graphs. Furthermore, several open questions that suggest interesting lines for future research are also proposed.2014-05-09T09:45:58ZThe (Delta,D) and (Delta,N) problems in double-step digraphs with unilateral distance
http://hdl.handle.net/2117/22938
Title: The (Delta,D) and (Delta,N) problems in double-step digraphs with unilateral distance
Authors: Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel
Abstract: We study the (delta;D) and (delta;N) problems for double-step digraphs considering the unilateral distance, which is the minimum between the distance in the digraph and the distance in its converse digraph, the latter obtained by changing the directions of all the arcs. The first problem consists of maximizing the number of vertices N of a digraph, given the
maximum degree and the unilateral diameter D , whereas the second one (somehow dual of the first) consists of minimizing the unilateral diameter given the maximum degree and the number of vertices. We solve the first problem for every value of the unilateral diameter and the second one
for infinitely many values of the number of vertices. Moreover, we compute the mean unilateral distance of the digraphs in the families considered.2014-05-09T09:30:19ZCorrigendum to "Algebraic characterizations of regularity properties in bipartite graphs" Eur. J. Combin. 34 (2013) 1223-1231
http://hdl.handle.net/2117/22446
Title: Corrigendum to "Algebraic characterizations of regularity properties in bipartite graphs" Eur. J. Combin. 34 (2013) 1223-1231
Authors: Abiad, Aida; Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel
Description: Corrigendum d'un article anteriorment publicat2014-03-31T10:03:52ZThe (Delta,D) and (Delta,N) problems in double-step digraphs with unilateral diameter
http://hdl.handle.net/2117/22316
Title: The (Delta,D) and (Delta,N) problems in double-step digraphs with unilateral diameter
Authors: Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel
Abstract: We study the (D;D) and (D;N) problems for double-step digraphs considering
the unilateral distance, which is the minimum between the distance in the digraph
and the distance in its converse digraph, obtained by changing the directions
of all the arcs.
The first problem consists of maximizing the number of vertices N of a digraph,
given the maximum degree D and the unilateral diameter D , whereas the
second one consists of minimizing the unilateral diameter given the maximum
degree and the number of vertices. We solve the first problem for every value
of the unilateral diameter and the second one for some infinitely many values of
the number of vertices.
Miller and Sirán [4] wrote a comprehensive survey about (D;D) and (D;N)
problems. In particular, for the double-step graphs considering the standard
diameter, the first problem was solved by Fiol, Yebra, Alegre and Valero [3],
whereas Bermond, Iliades and Peyrat [2], and also Beivide, Herrada, Balcázar
and Arruabarrena [1] solved the (D;N) problem. In the case of the double-step
digraphs, also with the standard diameter, Morillo, Fiol and Fàbrega [5] solved
the (D;D) problem and provided some infinite families of digraphs which solve
the (D;N) problem for their corresponding numbers of vertices2014-03-20T13:31:57ZAlgebraic Characterizations of Regularity Properties in Bipartite Graphs
http://hdl.handle.net/2117/22312
Title: Algebraic Characterizations of Regularity Properties in Bipartite Graphs
Authors: Abiad Monge, Aida; Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel
Abstract: Regular and distance-regular characterizations of general graphs are well-known. In particular, the spectral excess theorem states that a connected graph GG is distance-regular if and only if its spectral excess (a number that can be computed from the spectrum) equals the average excess (the mean of the numbers of vertices at extremal distance from every vertex). The aim of this paper is to derive new characterizations of regularity and distance-regularity for the more restricted family of bipartite graphs. In this case, some characterizations of (bi)regular bipartite graphs are given in terms of the mean degrees in every partite set and the Hoffman polynomial. Moreover, it is shown that the conditions for having distance-regularity in such graphs can be relaxed when compared with general graphs. Finally, a new version of the spectral excess theorem for bipartite graphs is presented.2014-03-20T12:40:12ZEdge-distance-regular graphs are distance-regular
http://hdl.handle.net/2117/22307
Title: Edge-distance-regular graphs are distance-regular
Authors: Cámara Vallejo, Marc; Dalfó Simó, Cristina; Delorme, Charles; Fiol Mora, Miquel Àngel; Suzuki, Hiroshi
Abstract: A graph is edge-distance-regular when it is distance-regular around each of its edges and it has the same intersection numbers for any edge taken as a root. In this paper we give some (combinatorial and algebraic) proofs of the fact that every edge-distance-regular graph Γ is distance-regular and homogeneous. More precisely, Γ is edge-distance-regular if and only if it is bipartite distance-regular or a generalized odd graph. Also, we obtain the relationships between some of their corresponding parameters, mainly, the distance polynomials and the intersection numbers.2014-03-20T10:40:00ZEnergy and carbon emissions aware services allocation with delay for Data Centers
http://hdl.handle.net/2117/22066
Title: Energy and carbon emissions aware services allocation with delay for Data Centers
Authors: Guillén, Bernat; Hesselbach Serra, Xavier; Muñoz López, Francisco Javier; Klingert, Sonja
Abstract: This paper presents a new approach to service
assignment in Data Centers (DC), relating it to a classical
combinatory problem called Bin Packing Problem and adding
the possibility of delay and collaboration with users and energy
providers. This possibility proves to reduce in much the energy
consumption of the DC as well as the CO2 emissions.2014-03-14T13:05:00ZConnectivity: properties and structure
http://hdl.handle.net/2117/22004
Title: Connectivity: properties and structure
Authors: Balbuena Martínez, Maria Camino Teófila; Fàbrega Canudas, José; Fiol Mora, Miquel Àngel
Abstract: Connectivity is one of the central concepts of graph theory, from both a theoret- ical and a practical point of view. Its theoretical implications are mainly based on the existence of nice max-min characterization results, such as Menger’s theorems. In these theorems, one condition which is clearly necessary also turns out to be sufficient. Moreover, these results are closely related to some other key theorems in graph theory: Ford and Fulkerson’s theorem about flows and Hall’s theorem on perfect matchings. With respect to the applications, the study of connectivity parameters of graphs and digraphs is of great interest in the design of reliable and fault-tolerant interconnection or communication networks.
Since graph connectivity has been so widely studied, we limit ourselves here to the presentation of some of the key results dealing with finite simple graphs and digraphs. For results about infinite graphs and connectivity algorithms the reader can consult, for instance, Aharoni and Diestel [AhDi94], Gibbons [Gi85], Halin [Ha00], Henzinger, Rao, and Gabow [HeRaGa00], Wigderson [Wi92]. For further details, we refer the reader to some of the good textbooks and surveys available on the subject: Berge [Be76], Bermond, Homobono, and Peyrat [BeHoPe89], Frank [Fr90, Fr94, Fr95], Gross and Yellen [GrYe06], Hellwig and Volkmann [HeVo08], Lov ´asz [Lo93], Mader [Ma79], Oellermann [Oe96], Tutte [Tu66].2014-03-12T12:00:55ZFurther topics in connectivity
http://hdl.handle.net/2117/22000
Title: Further topics in connectivity
Authors: Balbuena Martínez, Maria Camino Teófila; Fàbrega Canudas, José; Fiol Mora, Miquel Àngel
Abstract: Continuing the study of connectivity, initiated in §4.1 of the Handbook, we survey here some (sufficient) conditions under which a graph or digraph has a given connectivity or edge-connectivity. First, we describe results concerning maximal (vertex- or edge-) connectivity. Next, we deal with conditions for having (usually lower) bounds for the connectivity parameters. Finally, some other general connectivity measures, such as one instance of the so-called “conditional connectivity,” are considered.
For unexplained terminology concerning connectivity, see §4.1.2014-03-12T11:17:54ZFrom clutters to matroids
http://hdl.handle.net/2117/21963
Title: From clutters to matroids
Authors: Fàbrega Canudas, José; Martí Farré, Jaume; Muñoz López, Francisco Javier
Abstract: This paper deals with the question of completing a monotone increasing family of subsets to obtain the dependent sets of a matroid. More precisely, we provide several natural ways of transforming the clutter of the inclusion minimal subsets of the family into the set of circuits of a matroid.2014-03-10T12:57:39ZLocating domination in graphs and their complements
http://hdl.handle.net/2117/21284
Title: Locating domination in graphs and their complements
Authors: Hernando Martín, María del Carmen; Mora Giné, Mercè; Pelayo Melero, Ignacio Manuel
Abstract: A dominating set
S
of a graph
G
is called
locating-dominating
,
LD-set
for
short, if every vertex
v
not in
S
is uniquely determined by the set of neighbors of
v
belonging to
S
. Locating-dominating sets of minimum cardinality are called
LD
-codes
and the cardinality of an LD-code is the
location-domination number
. An LD-set of a
graph
G
is
global
if
S
is an LD-set of both
G
and its complement,
G
. In this work, we give
some relations between the locating-dominating sets and location-domination number in
a graph and its complement2014-01-20T12:49:27ZNordhaus-Gaddum bounds for locating domination
http://hdl.handle.net/2117/21023
Title: Nordhaus-Gaddum bounds for locating domination
Authors: Hernando Martín, María del Carmen; Mora Giné, Mercè; Pelayo Melero, Ignacio Manuel
Abstract: A dominating set S of graph G is called metric-locating–dominating if it is also locating, that is, if every vertex v is uniquely determined by its vector of distances to the vertices in S. If moreover, every vertex v not in S is also uniquely determined by the set of neighbors of v belonging to S, then it is said to be locating–dominating. Locating, metric-locating–dominating and locating–dominating sets of minimum cardinality are called β-codes, η-codes and λ-codes, respectively. A Nordhaus–Gaddum bound is a tight lower or upper bound on the sum or product of a parameter of a graph G and its complement View the MathML source. In this paper, we present some Nordhaus–Gaddum bounds for the location number β, the metric-location–domination number η and the location–domination number λ. Moreover, in each case, the graph family attaining the corresponding bound is fully characterized.2013-12-17T11:50:01ZSome structural, metric and convex properties of the boundary of a graph
http://hdl.handle.net/2117/20898
Title: Some structural, metric and convex properties of the boundary of a graph
Authors: Hernando Martín, María del Carmen; Mora Giné, Mercè; Pelayo Melero, Ignacio Manuel; Seara Ojea, Carlos
Abstract: Let
u;v
be two vertices of a connected graph
G
. The vertex
v
is
said to be a
boundary vertex
of
u
if no neighbor of
v
is further away
from
u
than
v
. The boundary of a graph is the set of all its boundary
vertices. In this work, we present a number of properties of the
boundary of a graph under diÆerent points of view: (1) a realization
theorem involving diÆerent types of boundary vertex sets: extreme
set, periphery, contour, and the whole boundary; (2) the contour is a
monophonic set; and (3) the cardinality of the boundary is an upper
bound for both the metric dimension and the determining number
of a graph2013-12-03T12:14:54ZLocating-dominating codes: Bounds and extremal cardinalities
http://hdl.handle.net/2117/20810
Title: Locating-dominating codes: Bounds and extremal cardinalities
Authors: Cáceres, Jose; Hernando Martín, María del Carmen; Mora Giné, Mercè; Pelayo Melero, Ignacio Manuel; Puertas, M. Luz
Abstract: In this work, two types of codes such that they both dominate and locate the vertices of a graph are studied. Those codes might be sets of detectors in a network or processors controlling a system whose set of responses should determine a malfunctioning processor or an intruder. Here, we present our contributions on λ-codes and η-codes concerning bounds, extremal values and realization theorems.2013-11-27T11:55:50Z