simulating multivariate nonnormal distributions a method for generating multivariate nonnormal distributions with specified intercorrelations and marginal means variances skews and kurtoses is proposed as an example the method is applied to the generation of simulated scores on three psychological tests administered to a single group of individuals

the embedding of an ordered groupoid into a poe groupoid in terms of fuzzy sets in this paper we prove that if s is an ordered groupoid resp ordered semigroup then the set f of all fuzzy subsets of s is a poe groupoid resp poe semigroup and s is embedded in f a poe groupoid is an ordered groupoid having a greatest element e i e e a a s

a new view of fuzzy hypernear rings in this survey article we first introduce the concept of quasi coincidence of a fuzzy interval value with an interval valued fuzzy set this concept is a generalized concept of quasi coincidence of a fuzzy point within a fuzzy set by using this new idea we consider the interval valued q fuzzy sub hypernear rings hyperideals of a hypernear ring and hence a generalization of a fuzzy sub near ring ideal is given some related properties of fuzzy hypernear rings are described finally we consider the concept of implication based interval valued fuzzy sub hypernear rings hyperideals in a hypernear ring in particular the implication operators in lukasiewicz system of continuous valued logic are discussed

fuzzy bi ideals in ordered semigroups given a set s a fuzzy subset of s is by definition an arbitrary mapping f s 0 1 where 0 1 is the unit segment of the real line if the set s bears some structure one may distinguish some fuzzy subsets of s in terms of that additional structure this important concept was first introduced by zadeh fuzzy groups have been first considered by rosenfelt fuzzy semigroups by kuroki a theory of fuzzy sets on ordered groupoids and ordered semigroups can be developed in the present paper we endow s with the structure of an ordered semigroup and define fuzzy analogous for several notions that have been proved to be useful in the theory of ordered semigroups we define the fuzzy bi ideals in ordered semigroups and we give the main theorem which characterizes the bi ideals in terms of fuzzy bi ideals then we characterize the left and right simple the completely regular and the strongly regular ordered semigroups by means of fuzzy bi ideals we also study the decomposition of left and right simple ordered semigroups and of ordered semigroups having the property a a2 for all a in terms of fuzzy bi ideals this decomposition is uniquely defined

repetiveness of languages generated by morphisms abstract we study the repetition of subwords in languages generated by morphisms fundamental to our approach is the notion of quasi repetitive elements using these elements we present a new characterization for repetitive morphisms from which we derive a simple proof for the fact that a d0l language is repetitive if and only if it is strongly repetitive ehrenfeucht and rozenberg inform and control 59 1983 13 35 from this proof we obtain a structurally simple polynomial time algorithm for deciding whether such a language is repetitive from further results on quasi repetitive elements we obtain as a consequence a complete characterization for all those morphisms on a two letter alphabet that are repetitive a result which is closely related to a result of seebold bull eatcs 36 1988 137 151 on the d0l periodicity problem finally we characterize those morphisms f on a two letter alphabet for which the language l f generated by f or the language sl f of subwords of l f are context free or even regular

regular ordered semigroups in terms of fuzzy subsets given a set s a fuzzy subset of s or a fuzzy set in s is by definition an arbitrary mapping f s 0 1 where 0 1 is the usual interval of real numbers if the set s bears some structure one may distinguish some fuzzy subsets of s in terms of that additional structure this important concept of a fuzzy set was first introduced by zadeh fuzzy groups have been first considered by rosenfeld fuzzy semigroups by kuroki a theory of fuzzy sets on ordered groupoids and ordered semigroups can be developed some results on ordered groupoids semigroups have been already given by the same authors in n kehayopulu m tsingelis fuzzy sets in ordered groupoids semigroup forum 65 2002 128 132 n kehayopulu m tsingelis the embedding of an ordered groupoid into a poe groupoid in terms of fuzzy sets inform sci 152 2003 231 236 n kehayopulu m tsingelis fuzzy bi ideals in ordered semigroups inform sci 171 2004 13 28 where s has been endowed with the structure of an ordered semigroup and defined fuzzy analogous for several notions that have been proved to be useful in the theory of ordered semigroups the characterization of regular rings in terms of right and left ideals is well known the characterization of regular semigroups and regular ordered semigroups in terms of left and right ideals or in terms of left right ideals and quasi ideals is well known as well the characterization of regular le semigroups that is lattice ordered semigroups having a greatest element in terms of right ideal elements and left ideal elements or right left and quasi ideal elements is also known in the present paper we first give the main theorem which characterizes the regular ordered semigroups by means of fuzzy right and fuzzy left ideals then we characterize the regular ordered semigroups in terms of fuzzy right fuzzy left ideals and fuzzy quasi ideals the paper serves as an example to show that one can pass from the theory of ordered semigroups to the theory of fuzzy ordered semigroups some of our results are true for ordered groupoids in general

redefined fuzzy hv submodules and many valued implications this paper considers a relationship between fuzzy sets and algebraic hyperstructures a generalization of ideas presented by davvaz b davvaz fuzzy h v submodules fuzzy sets syst 117 2001 477 484 and bhakat and das s k bhakat p das email protected q fuzzy subgroup fuzzy sets syst 80 1996 359 368 is presented in fact the main purpose of this paper is to introduce and study a new sort of fuzzy h v submodule of an h v module called email protected q fuzzy h v submodules these fuzzy h v submodules are characterized by their level h v submodules the concept of a fuzzy h v submodule with thresholds is introduced and some interesting properties are investigated

fuzzy ideals and fuzzy bi ideals in fuzzy semigroups abstract the purpose of this paper is to introduce some basic concepts of fuzzy algebra such as fuzzy left right ideal and fuzzy bi ideal in fuzzy semigroup through the new approach of fuzzy space and fuzzy group introduced by dib 1994 our notion of fuzzy ideal and fuzzy bi ideal includes the classical concepts of fuzzy ideal and fuzzy bi ideal of ordinary semigroup many counterexamples are also given

characterizations of ordered semigroups by the properties of their fuzzy ideals in this paper we characterize different classes of ordered semigroups by the properties of their ideals quasi ideals and bi ideals we also characterize these classes by the properties of their fuzzy ideals fuzzy quasi ideals and fuzzy bi ideals

repetition of subwords in dol languages a language k is repetitive if for each positive integer n there exists a word w such that w n is a subword of k language k is called strongly repetitive if there exists a word w such that for each positive integer n w n is a subword of k it is shown that it is decidable whether an arbitrary dol language is repetitive it is also shown that if a dol language is repetitive then it is strongly repetitive

fuzzy ideals in semigroups abstract the set of all fuzzy ideals of a semigroup is shown to be a convex set having the crisp ideals as extreme points some connections between fuzzy ideals and green s relations are discussed

simulation of massive public health data by power polynomials situations in which multiple outcomes and predictors of different distributional types are collected are becoming increasingly common in public health practice and joint modeling of mixed types has been gaining popularity in recent years evaluation of various statistical techniques that have been developed for mixed data in simulated environments necessarily requires joint generation of multiple variables most massive public health data sets include different types of variables for instance in clustered or longitudinal designs often multiple variables are measured or observed for each individual or at each occasion this work is motivated by a need to jointly generate binary and possibly non normal continuous variables we illustrate the use of power polynomials to simulate multivariate mixed data on the basis of a real adolescent smoking study we believe that our proposed technique for simulating such intensive data has potential to be a handy methodological addition to public health researchers toolkit

gaussianization based quasi imputation and expansion strategies for incomplete correlated binary responses new quasi imputation and expansion strategies for correlated binary responses are proposed by borrowing ideas from random number generation the core idea is to convert correlated binary outcomes to multivariate normal outcomes in a sensible way so that re conversion to the binary scale after performing multiple imputation yields the original specified marginal expectations and correlations this conversion process ensures that the correlations are transformed reasonably which in turn allows us to take advantage of well developed imputation techniques for gaussian outcomes we use the phrase quasi because the original observations are not guaranteed to be preserved we argue that if the inferential goals are well defined it is not necessary to strictly adhere to the established definition of multiple imputation our expansion scheme employs a similar strategy where imputation is used as an intermediate step it leads to proportionally inflated observed patterns forcing the data set to a complete rectangular format the plausibility of the proposed methodology is examined by applying it to a wide range of simulated data sets that reflect alternative assumptions on complete data populations and missing data mechanisms we also present an application using a data set from obesity research we conclude that the proposed method is a promising tool for handling incomplete longitudinal or clustered binary outcomes under ignorable non response mechanisms

on fuzzy ideals and fuzzy bi ideals in semigroups abstract in this paper we give some properties of fuzzy ideals and fuzzy bi ideals of semigroups and characterize semigroups that are left duo left simple and semilattices of subsemigroups in terms of fuzzy ideals and fuzzy bi ideals

fuzzy generalized bi ideals in semigroups abstract we introduce the concept of a fuzzy generalized bi ideal of a semigroup which is an extension of the concept of a fuzzy bi ideal and of a nonfuzzy bi ideal and a nonfuzzy ideal of a semigroup and characterize regular semigroups and both intraregular and left quasiregular semigroups in terms of fuzzy generalized bi ideals

multiple imputation under bayesianly smoothed pattern mixture models for non ignorable drop out conventional pattern mixture models can be highly sensitive to model misspecification in many longitudinal studies where the nature of the drop out and the form of the population model are unknown interval estimates from any single pattern mixture model may suffer from undercoverage because uncertainty about model misspecification is not taken into account in this article a new class of bayesian random coefficient pattern mixture models is developed to address potentially non ignorable drop out instead of imposing hard equality constraints to overcome inherent inestimability problems in pattern mixture models we propose to smooth the polynomial coefficient estimates across patterns using a hierarchical bayesian model that allows random variation across groups using real and simulated data we show that multiple imputation under a three level linear mixed effects model which accommodates a random level due to drop out groups can be an effective method to deal with non ignorable drop out by allowing model uncertainty to be incorporated into the imputation process

fuzzy semiprime ideals in semigroups abstract in this paper we shall introduce the notion of fuzzy semiprimality in a semigroup which is an extension of semiprimality in it and characterize a semigroup that is a semilattice of simple semigroups in terms of fuzzy semiprimality

proof of dejean s conjecture for alphabets with 5 6 7 8 9 10 and 11 letters abstract axel thue proved that overlapping factors could be avoided in arbitrarily long words on a two letter alphabet while on the same alphabet square factors always occur in words longer than 3 francoise dejean stated an analogous result for three letter alphabets every long enough word has a factor which is a fractional power with an exponent at least 7 4 and there exist arbitrary long words in which no factor is a fractional power with an exponent strictly greater than 7 4 the number 7 4 is called the repetition threshold of the three letter alphabets thereafter she proposed the following conjecture the repetition threshold of the k letter alphabets is equal to k k 1 except in the particular cases k 3 where this threshold is 7 4 and k 4 where it is 7 5 for k 4 this conjecture was proved by j j pansiot 1984 in this paper we give a computer aided proof of dejean s conjecture for several other values 5 6 7 8 9 10 and 11

on fuzzy semigroups abstract we give some propertes of fuzzy ideals and fuzzy biideals of a semigroup and characterize a regular semigroup a semigroup that is a semilattice of left right simple semigroups a semigroup that is a semilattice of left right groups and a semigroup that is a semilattice of groups in terms of fuzzy left right and two sided ideals and biideals

redefined fuzzy implicative filters using the belongs to relation and quasi coincidence with relation q between fuzzy points and fuzzy sets the concept of q j fuzzy implicative filters where q j are any two of q email protected q email protected q with q email protected q is introduced and related properties are discussed relations between email protected q email protected q fuzzy implicative filters and email protected q fuzzy implicative filters are investigated and conditions for an email protected q fuzzy implicative filter to be an fuzzy implicative filter are provided characterizations of email protected q fuzzy implicative filters are given and conditions for a fuzzy set to be a q email protected q fuzzy implicative filter are provided

on the subword complexity of square free dol languages abstract the subword complexity of a language k is the function which to every positive integer n assigns the number of different subwords of length n occuring in words of k a language k is square free if no word in it contains a subword of the form xx where x is a nonempty word the best upper and lower bounds on the subword complexity of infinite square free dol languages are established

an imputation strategy for incomplete longitudinal ordinal data a new quasi imputation strategy for correlated ordinal responses is proposed by borrowing ideas from random number generation the essential idea is collapsing ordinal levels to binary ones and converting correlated binary outcomes to multivariate normal outcomes in a sensible way so that re conversion to the binary and then ordinal scale after conducting multiple imputation yields the original marginal distributions and correlations this conversion process ensures that the correlations are transformed reasonably which in turn allows us to take advantage of well developed imputation techniques for gaussian outcomes we use the phrase quasi because the original observations are not guaranteed to be preserved we present an application using a data set from psychiatric research we conclude that the proposed method may be a promising tool for handling incomplete longitudinal or clustered ordinal outcomes

periodic d0l languages abstract periodic d0l systems and languages are defined and periodicity is shown to be a decidable property of d0l systems the fundamental tools used are recent results on the representation of stationary words head and lando 1986 and the decidability of ultimate periodicity of words harju and linna 1986 pansiot 1986 the relation of d0l periodicity to local catenativity and to n codes is examined

some remarks about stabilizers we continue our study of stabilizers of infinite words over finite alphabets begun in d krieger on stabilizers of infinite words theoret comput sci 400 2008 169 181 let w be an aperiodic infinite word over a finite alphabet and let stab w be its stabilizer we show that stab w can be partitioned into the monoid of morphisms that stabilize w by finite fixed points and the ideal of morphisms that stabilize w by iteration we also settle a conjecture given in the paper mentioned above by showing that in some cases stab w is infinitely generated if the aforementioned ideal is nonempty then it contains either polynomially growing morphisms or exponentially growing morphisms but not both moreover in the polynomial case the degree of the polynomial is fixed we also show how to compute the polynomial degree from the dependency graph of a polynomially growing morphism

an application of a mixed effects location scale model for analysis of ecological momentary assessment ema data for longitudinal data mixed models include random subject effects to indicate how subjects influence their responses over repeated assessments the error variance and the variance of the random effects are usually considered to be homogeneous these variance terms characterize the within subjects i e error variance and between subjects i e random effects variance variation in the data in studies using ecological momentary assessment ema up to 30 or 40 observations are often obtained for each subject and interest frequently centers around changes in the variances both within and between subjects in this article we focus on an adolescent smoking study using ema where interest is on characterizing changes in mood variation we describe how covariates can influence the mood variances and also extend the standard mixed model by adding a subject level random effect to the within subject variance specification this permits subjects to have influence on the mean or location and variability or square of the scale of their mood responses additionally we allow the location and scale random effects to be correlated these mixed effects location scale models have useful applications in many research areas where interest centers on the joint modeling of the mean and variance structure

generalized fuzzy interior ideals in semigroups using the idea of quasi coincidence of a fuzzy point with a fuzzy set the concept of an a b fuzzy interior ideal which is a generalization of a fuzzy interior ideal in a semigroup is introduced and related properties are investigated

restoring definiteness via shrinking with an application to correlation matrices with a fixed block indefinite approximations of positive semidefinite matrices arise in various data analysis applications involving covariance matrices and correlation matrices we propose a method for restoring positive semidefiniteness of an indefinite matrix m 0 that constructs a convex linear combination s alpha alpha m 1 1 alpha m 0 of m 0 and a positive semidefinite target matrix m 1 in statistics this construction for improving an estimate m 0 by combining it with new information in m 1 is known as shrinking we make no statistical assumptions about m 0 and define the optimal shrinking parameter as alpha min alpha in 0 1 s alpha is positive semidefinite we describe three alg s for computing alpha one algorithm is based on the bisection method with the use of cholesky factorization to test definiteness a second employs newton s method and a third finds the smallest eigenvalue of a symmetric definite generalized eigenvalue problem we show that weights that r

a family of multivariate binary distributions for simulating correlated binary variables with specified marginal means and correlations summary we introduce a family of multivariate binary distributions with certain conditional linear property this family is particularly useful for efficient and easy simulation of correlated binary variables with a given marginal mean vector and correlation matrix

fuzzy h ideals of hemirings a characterization of an h hemiregular hemiring in terms of a fuzzy h ideal is provided some properties of prime fuzzy h ideals of h hemiregular hemirings are investigated it is proved that a fuzzy subset z of a hemiring s is a prime fuzzy left right h ideal of s if and only if z is two valued z 0 1 and the set of all x in s such that z x 1 is a prime left right h ideal of s finally the similar properties for maximal fuzzy left right h ideals of hemirings are considered

on critical exponents in fixed points of non erasing morphisms let s be an alphabet of size t let f s s be a non erasing morphism let w be an infinite fixed point of f and let e w be the critical exponent of w we prove that if e w is finite then for a uniform f it is rational and for a non uniform f it lies in the field extension q r l 1 l where r l 1 l are the eigenvalues of the incidence matrix of f in particular e w is algebraic of degree at most t under certain conditions our proof implies an algorithm for computing e w

fuzzy semiprime quasi ideals in semigroups abstract we give some properties of fuzzy quasi ideals of a semigroup and characterize a completely regular semigroup and a semigroup that is a semilattice of groups in terms of fuzzy semiprime quasi ideals