We consider n-dimensional semi-algebraic spatial databases. We compute in first-order logic extended with a transitive closure operator, a linear spatial database which characterizes the semi-algebraic spatial database up to a homeomorphism. In this way, we generalize our earlier results to semi-algebraic spatial databases in arbitrary dimensions, our earlier results being true for only two dim...

1. Introduction. In [4]2 the elements of a Banach algebra are separated into various classes: the regular elements, the singular elements , the null divisors, the generalized null divisors, and so forth. These classes and their interrelations are then studied in detail. In [5] transformations between Banach spaces are studied and the classes of [4], after suitable generalization, are characteri...

In accordance with Tarski point of view, in this chapter the theory of closure operators is proposed as a unifying tool for fuzzy logics. Indeed, let F be the set of formulas of a given language. Then an abstract fuzzy logic is defined by a fuzzy semantics (i.e. a class of valuations of the formulas in F) and by a closure operator in the lattice of the fuzzy subsets of F (we call deduction oper...

We consider the Fokker–Planck operator with a strong external magnetic field. show maximal type estimate on this using nilpotent approach vector field polynomial operators and including notion of representation Lie algebra. This makes it possible to give an optimal characterization domain closure considered operator.

In this paper, the local function, weak semi-local function and closure are compared with each other according to inclusion relation. We define a new operator by using investigate its properties. Thanks operator, we obtain two topologies which finer than some previously defined topologies.

First introduced in the study of the Sturmian words, the iterated palindromic closure was generalized to pseudopalindromes. This operator allows one to construct words with infinitely many pseudopalindromic prefixes, called pseudostandard words. We provide here several combinatorial properties of the fixed points under the iterated pseudopalindromic closure.

The Abiteboul and Beeri algebra for complex objects can express a query whose meaning is transitive closure, but the algorithm naturally associated to this query needs exponential space. We show that any other query in the algebra which expresses transitive closure needs exponential space. This proves that in general the powerset is an intractable operator for implementing xpoint queries.

A constructively valid counterpart to Bourbaki’s Fixpoint Lemma for chaincomplete partially ordered sets is presented to obtain a condition for one closure system in a complete lattice L to be stable under another closure operator of L. This is then used to deal with coproducts and other aspects of frames.

In this work a general closure for the conductive electron heat flux parallel to an inhomogeneous magnetic field is derived and examined. Free-streaming and collisional effects are present in the drift kinetic equation which is solved using an expansion of eigenfunctions of the bounce-averaged, pitch-angle scattering operator. For bounce times short compared to transit and collision times, the ...

background: it has been estimated that 67 million people worldwide are affected with a primary glaucoma and that one-third have primary angle closure glaucoma. we aimed to determine the biometric differences between the eyes of patients with acute attack of primary angle closure and their non-involved fellow eyes.   methods: twenty eight patients with acute attack of primary angle closure were ...