Search results for "combinatoric"

"Table 1" of "$\Lambda$ polarization in associated K$^+$ - $\Lambda$ electro-production"

2000

LAMBDA polarization, with respect to the p_gamma x p_k axis.

On The Least Number of Palindromes in an Infinite Word

2012

On Approximate Jumbled Pattern Matching in Strings

2011

Given a string s, the Parikh vector of s, denoted p(s), counts the multiplicity of each character in s. Searching for a match of a Parikh vector q in the text s requires finding a substring t of s with p(t) = q. This can be viewed as the task of finding a jumbled (permuted) version of a query pattern, hence the term Jumbled Pattern Matching. We present several algorithms for the approximate version of the problem: Given a string s and two Parikh vectors u, v (the query bounds), find all maximal occurrences in s of some Parikh vector q such that u <= q <= v. This definition encompasses several natural versions of approximate Parikh vector search. We present an algorithm solving this problem …

Partial isometries and the conjecture of C.K. Fong and S.K. Tsui

2016

Abstract We investigate some bounded linear operators T on a Hilbert space which satisfy the condition | T | ≤ | Re T | . We describe the maximum invariant subspace for a contraction T on which T is a partial isometry to obtain that, in certain cases, the above condition ensures that T is self-adjoint. In other words we show that the Fong–Tsui conjecture holds for partial isometries, contractive quasi-isometries, or 2-quasi-isometries, and Brownian isometries of positive covariance, or even for a more general class of operators.

Cluster size distributions in particle systems with asymmetric dynamics

2001

We present exact and asymptotic results for clusters in the one-dimensional totally asymmetric exclusion process (TASEP) with two different dynamics. The expected length of the largest cluster is shown to diverge logarithmically with increasing system size for ordinary TASEP dynamics and as a logarithm divided by a double logarithm for generalized dynamics, where the hopping probability of a particle depends on the size of the cluster it belongs to. The connection with the asymptotic theory of extreme order statistics is discussed in detail. We also consider a related model of interface growth, where the deposited particles are allowed to relax to the local gravitational minimum.

Patterns in words and languages

2004

AbstractA word p, over the alphabet of variables E, is a pattern of a word w over A if there exists a non-erasing morphism h from E∗ to A∗ such that h(p)=w. If we take E=A, given two words u,v∈A∗, we write u⩽v if u is a pattern of v. The restriction of ⩽ to aA∗, where A is the binary alphabet {a,b}, is a partial order relation. We introduce, given a word v, the set P(v) of all words u such that u⩽v. P(v), with the relation ⩽, is a poset and it is called the pattern poset of v. The first part of the paper is devoted to investigate the relationships between the structure of the poset P(v) and the combinatorial properties of the word v. In the last section, for a given language L, we consider …

Spectral study of {R,s+1,k}- and {R,s+1,k,∗}-potent matrices

2020

Abstract The { R , s + 1 , k } - and { R , s + 1 , k , ∗ } -potent matrices have been studied in several recent papers. We continue these investigations from a spectral point of view. Specifically, a spectral study of { R , s + 1 , k } -potent matrices is developed using characterizations involving an associated matrix pencil ( A , R ) . The corresponding spectral study for { R , s + 1 , k , ∗ } -potent matrices involves the pencil ( A ∗ , R ) . In order to present some properties, the relevance of the projector I − A A # where A # is the group inverse of A is highlighted. In addition, some applications and numerical examples are given, particularly involving Pauli matrices and the quaterni…

Periodicity, morphisms, and matrices

2003

In 1965, Fine and Wilf proved the following theorem: if (fn)n≥0 and (gn)n≥0 are periodic sequences of real numbers, of period lengths h and k, respectively, and fn = gn for 0 ≤ n > h + k - gcd(h,k), then fn = gn for all n ≥ 0. Furthermore, the constant h + k - gcd(h,k) is best possible. In this paper, we consider some variations on this theorem. In particular, we study the case where fn ≤ gn, instead of fn = gn. We also obtain generalizations to more than two periods.We apply our methods to a previously unsolved conjecture on iterated morphisms, the decreasing length conjecture: if h : Σ* → Σ* is a morphism with |Σ|= n, and w is a word with |w| < |h(w)| < |h2(w)| < ... < |hk(w)|, then k ≤ n.

A multidimensional critical factorization theorem

2005

AbstractThe Critical Factorization Theorem is one of the principal results in combinatorics on words. It relates local periodicities of a word to its global periodicity. In this paper we give a multidimensional extension of it. More precisely, we give a new proof of the Critical Factorization Theorem, but in a weak form, where the weakness is due to the fact that we loose the tightness of the local repetition order. In exchange, we gain the possibility of extending our proof to the multidimensional case. Indeed, this new proof makes use of the Theorem of Fine and Wilf, that has several classical generalizations to the multidimensional case.

Sylow permutable subnormal subgroups of finite groups II

2001

[EN] In this paper a local version of Agrawal's theorem about the structure of finite groups in which Sylow permutability is transitive is given. The result is used to obtain new characterisations of this class of finite groups.