2,516 research outputs found
On slender 0L languages
AbstractWe give a complete proof of Theorem 3.1 in [2]. A pathological exception of Theorem 4.3 in [2] is exhibited and a condition to remove it is mentioned
Rewrite Closure and CF Hedge Automata
We introduce an extension of hedge automata called bidimensional context-free
hedge automata. The class of unranked ordered tree languages they recognize is
shown to be preserved by rewrite closure with inverse-monadic rules. We also
extend the parameterized rewriting rules used for modeling the W3C XQuery
Update Facility in previous works, by the possibility to insert a new parent
node above a given node. We show that the rewrite closure of hedge automata
languages with these extended rewriting systems are context-free hedge
languages
Spectrum of bound fermion states on vortices in He-B
We study subgap spectra of fermions localized within vortex cores in
He-B. We develop an analytical treatment of the low-energy states and
consider the characteristic properties of fermion spectra for different types
of vortices. Due to the removed spin degeneracy the spectra of all singly
quantized vortices consist of two different anomalous branches crossing the
Fermi level. For singular and vortices the anomalous branches are
similar to the standard Caroli-de Gennes -Matricon ones and intersect the Fermi
level at zero angular momentum yet with different slopes corresponding to
different spin states. On the contrary the spectral branches of nonsingular
vortices intersect the Fermi level at finite angular momenta which leads to the
appearance of a large number of zero modes, i.e. energy states at the Fermi
level. Considering the , and vortices with superfluid cores we
show that the number of zero modes is proportional to the size of the vortex
core.Comment: 6 pages, 1 figur
Motion of vortices in ferromagnetic spin-1 BEC
The paper investigates dynamics of nonsingular vortices in a ferromagnetic
spin-1 BEC, where spin and mass superfluidity coexist in the presence of
uniaxial anisotropy (linear and quadratic Zeeman effect). The analysis is based
on hydrodynamics following from the Gross-Pitaevskii theory. Cores of
nonsingular vortices are skyrmions with charge, which is tuned by uniaxial
anisotropy and can have any fractal value between 0 and 1. There are
circulations of mass and spin currents around these vortices. The results are
compared with the equation of vortex motion derived earlier in the
Landau-Lifshitz-Gilbert theory for magnetic vortices in easy-plane
ferromagnetic insulators. In the both cases the transverse gyrotropic force
(analog of the Magnus force in superfluid and classical hydrodynamics) is
proportional to the charge of skyrmions in vortex cores.Comment: 19 pages, 2 figures, to be published in the special issue of Fizika
Nizkikh Temperatur dedicated to A.M.Kosevich. arXiv admin note: substantial
text overlap with arXiv:1801.0109
k-Spectra of weakly-c-Balanced Words
A word is a scattered factor of if can be obtained from by
deleting some of its letters. That is, there exist the (potentially empty)
words , and such that and
. We consider the set of length- scattered
factors of a given word w, called here -spectrum and denoted
\ScatFact_k(w). We prove a series of properties of the sets \ScatFact_k(w)
for binary strictly balanced and, respectively, -balanced words , i.e.,
words over a two-letter alphabet where the number of occurrences of each letter
is the same, or, respectively, one letter has -more occurrences than the
other. In particular, we consider the question which cardinalities n=
|\ScatFact_k(w)| are obtainable, for a positive integer , when is
either a strictly balanced binary word of length , or a -balanced binary
word of length . We also consider the problem of reconstructing words
from their -spectra
Quantum, Stochastic, and Pseudo Stochastic Languages with Few States
Stochastic languages are the languages recognized by probabilistic finite
automata (PFAs) with cutpoint over the field of real numbers. More general
computational models over the same field such as generalized finite automata
(GFAs) and quantum finite automata (QFAs) define the same class. In 1963, Rabin
proved the set of stochastic languages to be uncountable presenting a single
2-state PFA over the binary alphabet recognizing uncountably many languages
depending on the cutpoint. In this paper, we show the same result for unary
stochastic languages. Namely, we exhibit a 2-state unary GFA, a 2-state unary
QFA, and a family of 3-state unary PFAs recognizing uncountably many languages;
all these numbers of states are optimal. After this, we completely characterize
the class of languages recognized by 1-state GFAs, which is the only nontrivial
class of languages recognized by 1-state automata. Finally, we consider the
variations of PFAs, QFAs, and GFAs based on the notion of inclusive/exclusive
cutpoint, and present some results on their expressive power.Comment: A new version with new results. Previous version: Arseny M. Shur,
Abuzer Yakaryilmaz: Quantum, Stochastic, and Pseudo Stochastic Languages with
Few States. UCNC 2014: 327-33
Additive decomposability of functions over abelian groups
Abelian groups are classified by the existence of certain additive
decompositions of group-valued functions of several variables with arity gap 2.Comment: 17 page
Currents on Superconducting Strings at Finite Chemical Potential and Temperature
We consider the model giving rise to Witten's superconducting cosmic strings
at finite fermion chemical potential and temperature. We demonstrate how
various symmetries of the hamiltonian can be used to exactly compute the
fermion electric current in the string background. We show that the current
along the string is not sensitive to the profiles of the string fields, and at
fixed chemical potential and temperature depends only on the string winding
number, the total gauge flux through the vortex and, possibly, the fermion mass
at infinity.Comment: 9 page
The Need for Effective Early Behavioral Family Interventions for Children with Attention Deficit Hyperactivity Disorder (ADHD)
There is a pressing need for the development of effective early family intervention programs for children showing Attention Deficit Hyperactivity Disorder (ADHD) behaviours with Conduct Disorder (CD) or Oppositional Defiant Disorder (ODD) behaviours. Previous research has indicated that children with ADHD are at risk of developing comorbid CD or ODD behaviours. In addition, it has been shown that ODD or CD behaviours in childhood tend to persist and to have adverse effects on later social adjustment. However, ODD or CD behaviours are not necessary concomitants of ADHD, and it has been demonstrated that behavioural intervention can have both short- and long term beneficial effects for children showing early signs of ODD or CD behaviours. In short term, behavioural family interventions may be able to reduce oppositional behaviour, particularly in the preschool years. In the long term, early intervention has shown to reduce the incidence of later antisocial behaviour in children at risk for this developmental trajectory. In this paper, it will be argued that behavioural family interventions have not been effectively utilised or promulgated in the community for children with ADHD despite the demonstrated efficacy of these types of interventions. A model of a multilevel system of intervention that can be tailored to the individual family’s needs is presented
On the effect of variable identification on the essential arity of functions
We show that every function of several variables on a finite set of k
elements with n>k essential variables has a variable identification minor with
at least n-k essential variables. This is a generalization of a theorem of
Salomaa on the essential variables of Boolean functions. We also strengthen
Salomaa's theorem by characterizing all the Boolean functions f having a
variable identification minor that has just one essential variable less than f.Comment: 10 page
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