the main goal of this paper is to introduce and study a new class of function via the notions of $e$-$theta$-open sets and $e$-$theta$-closure operator which are defined by özkoç and aslım cite{10} called weakly $er$-open functions and $e$-$theta$-open functions. moreover, we investigate not only some of their basic properties but also their relationships with other types of already existing to...

1.1 Definition. Let X be a nonempty set. A set c ⊂ P(X) is club in P(X) if there is a function f : X → X for which c is the set of A ⊂ X closed under f . Given a cardinal κ ≤ |X|, c is club in [X] (or in [X]) if c is the set of A ∈ [X] (or [X]) closed under f . A set a ⊂ P(X) is stationary in P(X) if it intersects every club subset of P(X), and stationary in [X] (or [X]) if it intersects every ...

in this paper, some categorical properties of the category ${bf cpo}_{{bf act}text{-}s}$ of all {cpo $s$-acts}, cpo's equipped with actions of a monoid $s$ on them, and strict continuous action-preserving maps between them is considered. in particular, we describe products and coproducts in this category, and consider monomorphisms and epimorphisms. also, we show that the forgetful functor from...

Let f be a diffeomorphism of a closed C∞ three-dimensional manifold. In this paper, we introduce the notion of C1-stably weak shadowing for a closed f -invariant set, and prove that C1-generically, for an aperiodic chain component Cf of f isolated in the chain recurrent set, if f|Cf is C 1-stably weak shadowing, then there are a C1-neighborhood U(f) of f and an open and dense subset V of U(f) s...

A line L separates a set A from a collection S of plane sets if A is contained in one of the closed half-planes defined by L, while every set in S is contained in the complementary closed half-plane. Let f(n) be the largest integer such that for any collection F of n closed disks in the plane with pairwise disjoint interiors, there is a line that separates a disk in F from a subcollection of F ...

In this article, we examine sets of lines in PG(d,F) meeting each hyperplane in a generator set of points. We prove that such a set has to contain at least 1.5d lines if the field F has more than 1.5d elements, and at least 2d− 1 lines if the field F is algebraically closed. We show that suitable 2d−1 lines constitute such a set (if |F| ≥ 2d−1), proving that the lower bound is tight over algebr...

In this article, we examine sets of lines in PG(d,F) meeting each hyperplane in a generator set of points. We prove that such a set has to contain at least b1.5dc lines if the field F has at least b1.5dc elements, and at least 2d− 1 lines if the field F is algebraically closed. We show that suitable 2d − 1 lines constitute such a set (if |F| > 2d − 1), proving that the lower bound is tight over...

Let (X, ‖ · ‖) be a real Banach space. Let C be a closed convex set in X. By a drop D(x, C) determined by a point x ∈ X, x / ∈ C, we shall mean the convex hull of the set {x} ∪ C. We say that C has the drop property if C 6= X and if for every nonvoid closed set A disjoint with C, there exists a point a ∈ A such that D(a, C) ∩ A = {a}. For a given C a sequence {xn} in X will be called a stream i...

2 Cohomology with Proper Supports In our étale cohomology setting, however, j! no longer sends injectives to injectives, and the isomorphism (1.1) may not hold. Consider the following example: Example 2.1. Consider f : AC → C. A closed subset of AC is either the entire line AC or a finite set of closed points, so for any sheaf F on AC, if a section s ∈ Γ(AC,F) has proper support, then supp(s) m...

A topological space X is said to be completely regular if whenever F is a nonempty closed set and x ∈ X \F , there is a continuous function f : X → [0, 1] such that f(x) = 0 and f(F ) = {1}. A completely regular space need not be Hausdorff. For example, ifX is any set with more than one point, then the trivial topology, in which the only closed sets are ∅ and X, is vacuously completely regular,...