Search results for "combinatoric"

A note on the exterior centralizer

2009

The notion of the exterior centralizer \({C_G^{^\wedge}(x)}\) of an element x of a group G is introduced in the present paper in order to improve some known results on the non-abelian tensor product of two groups. We study the structure of G by looking at that of \({C_G^{^\wedge}(x)}\) and we find some bounds for the Schur multiplier M(G) of G.

EXISTENCE OF THREE SOLUTIONS FOR A MIXED BOUNDARY VALUE PROBLEM WITH THE STURM-LIOUVILLE EQUATION

2012

Abstract. The aim of this paper is to establish the existence of threesolutions for a Sturm-Liouville mixed boundary value problem. The ap-proach is based on multiple critical points theorems. 1. IntroductionThe aim of this paper is to establish, under a suitable set of assumptions, theexistence of at least three solutions for the following Sturm-Liouville problemwith mixed boundary conditions(RS λ )ˆ−(pu ′ ) ′ +qu = λf(t,u) in I =]a,b[u(a) = u ′ (b) = 0,where λ is a positive parameter and p, q, f are regular functions. To be precise,if f : [a,b] × R→ Ris a L 2 -Carath´eodory function and p,q ∈ L ∞ ([a,b]) suchthatp 0 := essinf t∈[a,b] p(t) > 0, q 0 := essinf t∈[a,b] q(t) ≥ 0,then we prove …

Lower and Upper Probability Bounds for Some Conjunctions of Two Conditional Events

2018

In this paper we consider, in the framework of coherence, four different definitions of conjunction among conditional events. In each of these definitions the conjunction is still a conditional event. We first recall the different definitions of conjunction; then, given a coherent probability assessment (x, y) on a family of two conditional events \(\{A|H,B|K\}\), for each conjunction \((A|H) \wedge (B|K)\) we determine the (best) lower and upper bounds for the extension \(z=P[(A|H) \wedge (B|K)]\). We show that, in general, these lower and upper bounds differ from the classical Frechet-Hoeffding bounds. Moreover, we recall a notion of conjunction studied in recent papers, such that the res…

Automorphisms of simplicial complexes and their Stanley-Reisner rings

1997

Regular subclasses in the Sobolev space

2009

Abstract We study some slight modifications of the class α - A C n ( Ω , R m ) introduced in [D. Bongiorno, Absolutely continuous functions in R n , J. Math. Anal. and Appl. 303 (2005) 119–134]. In particular we prove that the classes α - A C λ n ( Ω , R m ) , 0 λ 1 , introduced in [C. Di Bari, C. Vetro, A remark on absolutely continuous functions in R n , Rend. Circ. Matem. Palermo 55 (2006) 296–304] are independent by λ and contain properly the class α - A C n ( Ω , R m ) . Moreover we prove that α - A C n ( Ω , R m ) = ( α - A C λ n ( Ω , R m ) ) ∩ ( α - A C n , λ ( Ω , R m ) ) , where α - A C n , λ ( Ω , R m ) is the symmetric class of α - A C λ n ( Ω , R m ) , 0 λ 1 .

The best constant for the Sobolev trace embedding from into

2004

Abstract In this paper we study the best constant, λ 1 ( Ω ) for the trace map from W 1 , 1 ( Ω ) into L 1 ( ∂ Ω ) . We show that this constant is attained in BV ( Ω ) when λ 1 ( Ω ) 1 . Moreover, we prove that this constant can be obtained as limit when p ↘ 1 of the best constant of W 1 , p ( Ω ) ↪ L p ( ∂ Ω ) . To perform the proofs we will look at Neumann problems involving the 1-Laplacian, Δ 1 ( u ) = div ( Du / | Du | ) .

${\cal H}^1$ -estimates of Jacobians by subdeterminants

2002

Let $f:\Omega \rightarrow{\Bbb R}^n$ be a mapping in the Sobolev space $W^{1,n-1}_{loc}(\Omega,{\Bbb R}^n), n\geq 2$ . We assume that the cofactors of the differential matrix Df(x) belong to $L^\frac{n}{n-1}(\Omega)$ . Then, among other things, we prove that the Jacobian determinant detDf lies in the Hardy space ${\cal H}^1(\Omega)$ .

Restriction of characters to Sylow normalizers

2001

Suppose that G is a finite p -solvable group and let \chi \in {\rm Irr}(G) be of p^\prime -degree. In this note, we investigate when \chi remains irreducible when restricted to {\bf {N)}_{G}(P) .

Counting degree sequences of spanning trees in bipartite graphs: A graph‐theoretic proof

2019

Entropic Profiles, Maximal Motifs and the Discovery of Significant Repetitions in Genomic Sequences

2014

The degree of predictability of a sequence can be measured by its entropy and it is closely related to its repetitiveness and compressibility. Entropic profiles are useful tools to study the under- and over-representation of subsequences, providing also information about the scale of each conserved DNA region. On the other hand, compact classes of repetitive motifs, such as maximal motifs, have been proved to be useful for the identification of significant repetitions and for the compression of biological sequences. In this paper we show that there is a relationship between entropic profiles and maximal motifs, and in particular we prove that the former are a subset of the latter. As a furt…