singular kahler einstein metrics we study degenerate complex monge ampere equations of the form omega dd c f n e t f mu where omega is a big semi kahler form on a compact kahler manifold x of dimension n t in r and mu f omega n is a positive measure with density f in l p x omega n p 1 we prove the existence and unicity of continuous o plurisubharmonic solutions in case x is projective and omega psi omega where psi x to v is a proper birational morphism to a normal projective variety omega in ns r v is an ample class and mu has only algebraic singularities we prove that the solution is smooth in the regular locus of the equation we use these results to construct singular kahler einstein metrics of non positive curvature on projective klt pairs in particular on canonical models of algebraic varieties of general type

oscillations of first order neutral delay differential equations abstract consider the neutral delay differential equation d dt y t py t qy t 0 t t 0 where q and are positive constants while p 1 0 for the case p 1 0 see ladas and sficas oscillations of neutral delay differential equations to appear the following results are then proved theorem 1 assume p and q 1 p 1 e then every solution of eq oscillates theorems 3 assume p 0 then every nonoscillatory solution y t of eq tends to zero as t theorem 4 assume p 0 then a necessary condition for all solutions of eq to oscillate is that theorem 5 assume p 0 and q 1 p 1 e then every solution of eq oscillates extensions of these results to equations with variable coefficients are also obtained

word indexing of ancient documents using fuzzy classification this paper proposes a fuzzy classification system to perform word indexing in ancient printed documents the indexing system receives a given word selected by an user the word is preprocessed using an aspect ratio filter assuring that only interesting word candidates are considered the image is classified by oriented feature extraction using gabor filter banks the oriented features are used to generate membership functions that characterize the selected word this target word image is then compared to the potential matches using a similarity matrix the indexing system is flexible and lightweight when compared to other optimal recognizers which allows its use in real time applications a significant test revealed that the indexer achieved very good results in terms of precision and recall in texts from xviith century

on the oscillation of an n th order nonlinear neutral delay differential equation abstract the authors consider the n th order nonlinear neutral delay differential equation y t p t y g t n q t f y h t 0 where n 1 q t 0 and 1 they give sufficient conditions for solutions to either oscillate or converge to zero

a necessary and sufficient condition for the oscillation of neutral equations abstract consider the neutral differential equation d dt y t py t qy t 0 t t 0 where p q and are real numbers then a necessary and sufficient condition for the oscillation of is that the characteristic equation p e qe 0 has no real roots

asymptotic and oscillatory behavior of solutions of first order nonlinear neutral delay differential equations the authors consider the first order nonlinear neutral delay differential equation e y t p t y t q t y t 0 where p q and are continuous q t 0 0 0 and u u 0 if u 0 they give sufficient conditions for all nonoscillatory solutions of e to converge to zero as t two oscillation theorems for equation e are also proved

fuzzy tolerance relations and relational maps applied to information retrieval one of the major problems in automatic indexing and retrieval of documents is that usually it cannot be guaranteed that the user queries include all of the actual words that occur in the documents that should be retrieved also it often happens that words with several meanings occur in a document but in a rather different context from that expected by the querying person in order to achieve better recall and higher precision fuzzy tolerance and similarity relations have been introduced based on the counted or estimated values of hierarchical co occurrence frequencies this study addresses the problem of how these relations can be generated from the occurrence frequencies especially as these are based on possibilistic rather than probabilistic measures and also how the relations can be implemented by fuzzy relevance matrices

new oscillation criteria for first order nonlinear neutral delay differential equations some new oscillation criteria of first order nonlinear neutral delay differential equations with variable coefficients are given our results extend and improve some of the well known previously results in the literature some examples are considered to illustrate our main results

an extension of the characterization of oscillations to arbitrary functional differential equations via the laplace transform in this paper we consider a functional differential equation of general form using the laplace transform we prove that such an equation has a nonoscillatory solution if and only if the characteristic equation has a real zero

canonical surfaces with big cotangent bundle surfaces of general type with positive second segre number are known to have big cotangent bundle we give a new criterion ensuring that a surface of general type with canonical singularities has a minimal resolution with big cotangent bundle this provides many examples of surfaces with negative second segre number and big cotangent bundle

necessary and sufficient conditions for oscillation of neutral equations with real coefficients abstract consider the neutral delay differential equation d dt y t py t q 1 y t 1 q 2 y t 2 0 where the coefficients p q1 q2 are real numbers and the delays 1 2 are nonnegative eal numbers we prove that every solution of eq 1 oscillates if and only if the characteristic equation pe q1e 1 q2e 2 0 has no real roots

oscillations caused by several retarded and advanced arguments in this paper we study the oscillatory behavior of equations of the forms y t i 1npiy t i 0 and y t i 1npiy t i 0 where piand i i 1 2 n are positive constants we prove that each one of the following conditions 1 pi i1 e for some i i 1 2 n 2 i 1npi 1 e where min 1 2 n 3 i 1npi 1 n i 1n i 1 e or 4 1 n i 1n pi i 1 2 21 e implies that every solution of and oscillates a generalization in the case where the coefficientspi i 1 2 n are positive and continuous functions is also presented

oscillation and nonoscillation in first order neutral differential equations abstract verifiable sufficient conditions are obtained respectively for the oscillation and nonoscillation of the neutral differential equation x t cx t px t 0

an oscillation test for a class of linear neutral differential equations where the following conditions are assumed to hold without further mention a h to co 0 co is continuous b t t cc p r is continuous increasing and satisfies lim oo r t cq c p cb co t 0 00 is continuous d g z co r is continuous and lim a g l cc in what follows by a solution of a or b we understand a continuous function x t co r such that x t h t x r t is continuously differentiable and satisfies a or b for all sufficiently large t 2 t as is customary we restrict our attention to those solutions x t of a or b which satisfy sup ix t t 2 t o

fuzzy information retrieval based on multi relationship fuzzy concept networks abstract in this paper we present a new method for fuzzy information retrieval based on multi relationship fuzzy concept networks there are four kinds of fuzzy relationships in a multi relationship fuzzy concept network i e fuzzy positive association relationship fuzzy negative association relationship fuzzy generalization relationship and fuzzy specialization relationship by performing fuzzy inferences based on the multi relationship fuzzy concept network the fuzzy information retrieval system can retrieve documents containing concepts that are not directly specified by the user but are somehow related to the user s query in order to perform fuzzy inferences more efficiently we use concept matrices to represent the degrees of fuzzy relationships between concepts in a multi relationship fuzzy concept network by calculating the transitive closures of concept matrices the implicit degrees of fuzzy relationships between concepts are obtained multiple degrees of satisfaction that a document satisfies the user s query with respect to the fuzzy relationships between concepts are calculated these satisfaction degrees are aggregated according to the user s specification to find the most relevant documents with respect to the user s query the proposed fuzzy information retrieval method is more flexible and more intelligent than the one we presented in ieee trans systems man cybernet part b cybernet 29 1 1999 126

when all solutions of x qi t x t ti t oscillate abstract in this paper the long term behavior of solutions to the equation in the title are examined where q i t and t i t are positive in particular it is shown that if lim inf t i 1 n t i t q i t 1 e all solutions oscillate about 0 infinitely often

oscillations of retarded differential equations of the neutral and the mixed types abstract this paper is devoted to the study of the oscillation of solutions of delay differential equations of the neutral and mixed types some general results are proved for certain general volterra type neutral differential equations and many particular cases are discussed

necessary and sufficient condition for oscillation of a neutral differential system with several delays abstract in this paper we prove that a general neutral differential system with several delays has a nonoscillatory solution if and only if its characteristic equations has a real root

necessary and sufficient conditions for oscillations of neutral equations with several coefficients consider the neutral equation with several positive and negative coefficients dd tx t ipix t i jrjx t j kqkx t k 0 1 where i j and k are initial segments of natural numbers pi i rj j qk are positive numbers and k 0 for i i j j and k k then a necessary and sufficient condition for the oscillation of all solutions of 1 is that its characteristic equation ipie i irje j kqke k 0 has no real roots

necessary and sufficient conditions for oscillations of neutral differential equations abstract consider the neutral delay differential equation x t px t qx t 0 t t 0 where q and are positive constants while p is a real parameter then a necessary and sufficient condition for all solutions of to oscillate is that the characteristic equation p e qe 0 of has no real roots

oscillation of first order neutral functional differential equations abstract some new sufficient conditions are obtained for oscillation of a kind of neutral differential equations these conditions improve some recent results

oscillations of delay differential equations with variable coefficients abstract consider the delay differential equation x t p t x t 0 where p t c t 0 r and is a positive constant we obtain a sharp sufficient condition for the oscillation of this equation which improves previously known results

a mixed neutral system on demontre des resultats d existence et d unicite pour le systeme d equations differentielles fonctionnelles suivant x t f t x j 1 m f j t x x t p j

ricci curvature minimal volumes and seiberg witten theory we derive new sharp lower bounds for certain curvature functionals on the space of riemannian metrics of a smooth compact 4 manifold with non trivial seiberg witten invariants these allow one for example to exactly compute the infimum of the l 2 norm of ricci curvature for any complex surface of general type we are also able to show that the standard metric on any complex hyperbolic 4 manifold minimizes volume among all metrics satisfying a point wise lower bound on sectional curvature plus suitable multiples of the scalar curvature these estimates also imply new non existence results for einstein metrics

constructions of kahler einstein metrics with negative scalar curvature we show that on kahler manifolds with negative first chern class the sequence of algebraic metrics introduced by tsuji converges uniformly to the kahler einstein metric for algebraic surfaces of general type and orbifolds with isolated singularities we prove a convergence result for a modified version of tsuji s iterative construction