Browsing by Author "Serra Albó, Oriol"

A mathematical model for dynamic memory networks
Fàbrega Canudas, José; Fiol Mora, Miquel Àngel; Serra Albó, Oriol; Andrés Yebra, José Luis (Iniciativa Digital Politècnica, 2011)
Conference report
Open AccessThe aim of this paper is to bring together the work done several years ago by M.A. Fiol and the other authors to formulate a quite general mathematical model for a kind of permutation networks known as dynamic memories. A ... 
An algebraic model for the storage of data in parallel memories
Fiol Mora, Miquel Àngel; Serra Albó, Oriol (Springer, 1989)
Part of book or chapter of book
Open AccessThe use of SIMD computers requires efficient schemes of storage of data in order to have conflictfree acces in parallel computation. In this paper we restate the problem of finding such chemes in an algebraic context. ... 
An analogue of Vosper's theorem for extension fields
Bachoc, Christine; Serra Albó, Oriol; Zemor, Gilles (20171101)
Article
Open AccessWe are interested in characterising pairs S, T of Flinear subspaces in a field extension L/F such that the linear span ST of the set of products of elements of S and of elements of T has small dimension. Our central result ... 
COMBINATÒRIA (Examen 1r quadrim)
Serra Albó, Oriol (Universitat Politècnica de Catalunya, 20090122)
Exam
Restricted access to the UPC academic community 
Combinàtoria i Teoria de Grafs
Serra Albó, Oriol (Universitat Politècnica de Catalunya, 20180109)
Exam
Restricted access to the UPC academic community 
Correlation among runners and some results on the lonely runner conjecture
Perarnau, Guillem; Serra Albó, Oriol (20161003)
Article
Open AccessThe Lonely Runner Conjecture, posed independently by Wills and by Cusick, states that for any set of runners running along the unit circle with constant different speeds and starting at the same point, there is a time where ... 
Counting configurationfree sets in groups
Rué Perna, Juan José; Serra Albó, Oriol; Vena Cros, Lluís (20170101)
Article
Open Access© 2017 Elsevier Ltd. We provide asymptotic counting for the number of subsets of given size which are free of certain configurations in finite groups. Applications include sets without solutions to equations in nonabelian ... 
Counting configuration–free sets in groups
Rué Perna, Juan José; Serra Albó, Oriol; Vena Cros, Lluís (2015)
Conference lecture
Restricted access  publisher's policyWe present a unified framework to asymptotically count the number of sets, with a given cardinality, free of certain configurations. This is done by combining the hypergraph containers methodology joint with arithmetic ... 
Cycle codes of graphs and MDS array codes
Serra Albó, Oriol; Zemor, Gilles (20090730)
Article
Restricted access  publisher's policyWe investigate how to colour edges of graph so that any two colours make up a spanning tree. This problem is equivalent to transforming the cycle code of a graph into a Maximum Distance Separable (MDS) array code. Adopting ... 
General properties of ccirculant digraphs
Mora Giné, Mercè; Serra Albó, Oriol; Fiol Mora, Miquel Àngel (1988)
Article
Open AccessA digraph is said to be a ccirculant if its adjacency matrix is ccirculant. This paper deals with general properties of this family of digraphs, as isomorphisms, regularity, strong connectivity, diameter and the relation ... 
Memorial to Javier Cilleruelo: A Problem list
Candela, Pablo; Rué Perna, Juan José; Serra Albó, Oriol (20180323)
Article
Open AccessThis is a list of problems in combinatorial number theory gathered on the occasion of the meeting The Music of Numbers to honor the memory of the late Javier Cilleruelo (19612016). 
On a problem by Shapozenko on Johnson Graphs
Diego Gutiérrez, Victor; Serra Albó, Oriol (201809)
Article
Restricted access  publisher's policyThe Johnson graph J(n, m) has the msubsets of {1,2,…,n} as vertices and two subsets are adjacent in the graph if they share m1 elements. Shapozenko asked about the isoperimetric function µn,m(k) of Johnson graphs, that ... 
On doubling and volume: chains
Freiman, Gregory A.; Serra Albó, Oriol (\Institute of Mathematics, Polish Academy of Sciences\, 20181001)
Article
Open AccessThe wellknown Freiman–Ruzsa theorem provides a structural description of a set A of integers with 2A=cA as a subset of a d–dimensional arithmetic progression P with P=c'A, where d and c' depend only on c. The ... 
On monochromatic solutions of equations in groups
Cameron, Peter J.; Cilleruelo, Javier; Serra Albó, Oriol (20060112)
Article
Open AccessResum no disponible 
On some groups related to arccolored digraphs
Serra Albó, Oriol; Fiol Mora, Miquel Àngel (Mediterranean press, 1988)
Conference lecture
Open AccessAn arccoloring of a digraph G is an assignation of colors to its arcs in such a way that all arcs incident to each vertex, as well as all arcs incident from each vertex, have different colors. In an arccolored dregular ... 
On sums of dilates
Javier, Cilleruelo; Hamidoune, Yahya ould; Serra Albó, Oriol (20091005)
Article
Open AccessFor k prime and A a finite set of integers with A ≥ $3(k1)^2$ (k1)! we prove that A+k·A ≥ (k+1)A − ⌈k(k+2)/4⌉ where k·A = {ka:a∈A}. We also describe the sets for which equality holds. 
On the number of monochromatic solutions of integer linear systems on Abelian groups
Serra Albó, Oriol; Vena, Lluis (20111201)
Article
Restricted access  publisher's policyLet G be a finite cyclic group an let r be a positive integer. Let A be a k×m matrix with integer entries. We show that, if A satisfies some natural conditions, then the homogeneous linear system Ax=0 has Ω(GNm−k) ... 
On the number of solutions of regular systems in sets with positive density in abelian groups
Král, Daniel; Serra Albó, Oriol; Vena, Lluis (2010)
Conference report
Restricted access  publisher's policyWe prove a density version for the Ramsey statement that, for fixed r and sufficiently large n, every coloring of an abelian group of order n with r colors has nontrivial monochromatic solutions of the system Ax = 0, where ... 
On the tree depth of random graphs
Perarnau Llobet, Guillem; Serra Albó, Oriol (2010)
Conference report
Restricted access  publisher's policyThe treedepth of a graph G is a parameter that plays a crucial role in the theory of bounded expansion classes and has been introduced under numerous names. We describe the asymptotic behaviour of this parameter in the ... 
Perspectivas en combinatoria
Noy Serrano, Marcos; Serra Albó, Oriol (Real Sociedad Matemática Española, 20161003)
Article
Open Access