Exploració per altres contribucions "Universitat Politècnica de Catalunya. GAPCOMB - Geometric, Algebraic and Probabilistic Combinatorics"
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A list of applications of stallings automata
(2022-11-22)
Article
Accés obertThis survey is intended to be a fast (and reasonably updated) reference for the theory of Stallings automata and its applications to the study of subgroups of the free group, with the main accent on algorithmic aspects. ... -
A polynomial-time reduction from the multi-graph isomorphism problem to additive codeequivalence
(2021-12-02)
Article
Accés obertWe present a polynomial-time reduction from the multi-graph isomorphism problem to the problem of code equivalence of additive codes over finite extensions of the field with two elements. -
A rainbow Dirac's theorem
(2020-01-01)
Article
Accés obertA famous theorem of Dirac states that any graph on n vertices with minimum degree at least n/2 has a Hamilton cycle. Such graphs are called Dirac graphs. Strengthening this result, we show the existence of rainbow Hamilton ... -
A removal lemma for systems of linear equations over finite fields
(2012-01)
Article
Accés obertWe prove a removal lemma for systems of linear equations over finite fields: let X1, . . . , Xm be subsets of the finite field Fq and let A be a (k × m) matrix with coefficients in Fq and rank k; if the linear system Ax = ... -
A step beyond Freiman’s theorem for set addition modulo a prime
(2020-01-01)
Article
Accés obertFreiman’s 2.4-Theorem states that any set A¿Zp satisfying |2A|=2.4|A|-3 and |A|<p/35 can be covered by an arithmetic progression of length at most |2A|-|A|+1. A more general result of Green and Ruzsa implies that this ... -
Acyclic edge colourings of graphs with large girth
(2016-11-03)
Article
Accés obertAn edge colouring of a graph G is called acyclic if it is proper and every cycle contains at least three colours. We show that for every e > 0, there exists a g = g(e) such that if G has maximum degree ¿ and girth at least ... -
Additive MDS codes
(2022)
Text en actes de congrés
Accés obertWe prove that an additive code over a finite field which has a few projections which are equivalent to a linear code is itself equivalent to a linear code, providing the code is not too short. -
Additive volume of sets contained in few arithmetic progressions
(De Gruyter, 2019-03-06)
Article
Accés obertA conjecture of Freiman gives an exact formula for the largest volume of a finite set A of integers with given cardinality k=|A| and doubling T=|2A|. The formula is known to hold when T=3k-4, for some small range over 3k-4 ... -
An approximate structure theorem for small sumsets
(Birkhäuser, 2021-08-24)
Capítol de llibre
Accés obertLet A and B be randomly chosen s-subsets of the first n integers such that their sumset A+B has size at most Ks. We show that asymptotically almost surely A and B are almost fully contained in arithmetic progressions PA ... -
An Erdös–Fuchs theorem for ordered representation functions
(2020-10-28)
Article
Accés obertLetk=2 be a positive integer. We study concentration results for the ordered representationfunctionsr=k(A, n) = #{(a1= ··· =ak)¿ Ak:a1+···+ak=n}andr<k(A, n) = #{(a1<···<ak)¿ Ak:a1+···+ak=n}for any infinite set ... -
An irrational-slope Thompson’s group
(2021-01-01)
Article
Accés obertThe purpose of this paper is to study the properties of the irrational-slope Thompson’s group Ft introduced by Cleary in [11]. We construct presentations, both finite and infinite, and we describe its combinatorial structure ... -
Approximation and decomposition in lattices of clutters
(2023-08-01)
Article
Accés obertA clutter on O is a family of subsets of O that are incomparable under inclusion. Given a collection S of clutters on O and another clutter ¿ on O, we study the problem of approximating and decomposing ¿ in terms of the ... -
Arcs and tensors
(2019-08-01)
Article
Accés obertTo an arc A of PG(k-1,q) of size q+k-1-t we associate a tensor in ¿¿k,t(A)¿¿k-1 , where ¿k,t denotes the Veronese map of degree t defined on PG(k-1,q) . As a corollary we prove that for each arc A in PG(k-1,q) of size ... -
Arcs in finite projective spaces
(2019-11-23)
Article
Accés restringit per política de l'editorialThis is an expository article detailing results concerning large arcs in finite projective spaces. It is not strictly a survey but attempts to cover the most relevant results on arcs, simplifying and unifying proofs of ... -
Asymptotics of sequences
(2017-12-01)
Capítol de llibre
Accés restringit per política de l'editorial -
Autòmats de Stallings, un camí d'anada i tornada
(2022-12-14)
Article
Accés obertEn aquest article revisem algunes de les propietats fonamentals del grup lliure i fem una exposició detallada de la teoria dels autòmats de Stallings, una interpretació geomètrica dels seus subgrups que ha estat (i segueix ... -
Big Ramsey degrees of 3-uniform hypergraphs
(2019)
Text en actes de congrés
Accés obertGiven a countably infinite hypergraph $\mathcal R$ and a finite hypergraph $\mathcal A$, the \emph{big Ramsey degree} of $\mathcal A$ in $\mathcal R$ isthe least number $L$ such that, for every finite $k$ and every ... -
Caracteritzant els codis de Gauss: només cal girar la cantonada
(2020-02-05)
Article
Accés obertAquest document està dedicat a la història, les motivacions i algunes solu-cions alproblema dels codis de Gauss.Una corba tancada al pla pot contenir punts d’autointersecció; en suposem unnombre finit, suposem els talls ... -
Chordal graphs with bounded tree-width
(Masaryk University, 2023)
Comunicació de congrés
Accés obertGiven $t\ge 2$ and $0\le k\le t$, we prove that the number of labelled $k$-connected chordal graphs with $n$ vertices and tree-width at most $t$ is asymptotically $c n^{-5/2} \gamma^n n!$, as $n\to\infty$, for some constants ... -
Commutators in groups of piecewise projective homeomorphisms
(2018-07-09)
Article
Accés obertIn [7] Monod introduced examples of groups of piecewise projective homeomorphisms which are not amenable and which do not contain free subgroups, and in [6] Lodha and Moore introduced examples of finitely presented groups ...