Volume 20, No. 2 (2010)

Articles

INDICATRIX OF A FINSLER VECTOR BUNDLE

We consider a Finsler vector bundle, i. e. a vector bundle ξ : (E,p,M) endowed with a smooth function F:E →IR; (x,y) → F(x,y), that is positively homogeneous of degree 1 with respect to the variables y in fibres of ξ. Then F(x; y) = 1 with a fixed x defines the indicatrix of the given Finsler bundle in the fibre Exand F(x; y) =1 for every x and y is its indicatrix bundle. We show in Section 2 that the indicatrix is a totally umbilical submanifold in Ex of constant mean curvature (-1). The indicatrix bundle is a submanifold of E \ 0 . Assuming that ξ is endowed with a nonlinear connection compatible with F and the base M is a Riemannian manifold, we define a Riemannian metric on E \ 0 and determine the normal to the indicatrix bundle.

ON qI-OPEN SETS IN IDEAL BITOPOLOGICAL SPACES

In this paper, we introduce and study the concept of qI-open set. Based on this new concept, we define new classes of functions, namely qI-continuous functions, qI-open functions and qI-closed functions, for which we prove characterization theorems.

SUPRA PRE-OPEN SETS AND SUPRA PRE-CONTINUITY ON TOPOLOGICAL SPACES

In this paper, a new class of sets and maps between topological spaces called supra pre-open sets and supra pre-continuous maps, respectively are introduced and studied. Furthermore, the concepts of supra pre-open maps and supra pre-closed maps in terms of supra pre-open sets and supra pre-closed sets, respectively, are introduced and several properties of them are investigated.

STRONGLY θ-PRE-I-CONTINUOUS FUNCTIONS

The topology τ of a space is enlarged to a topology τ* using an ideal I whose members are disjoint with the members of τ. Many relations between topological concepts with respect to τ and τ* are obtained. The aim of this paper is to define a new type of functions called strongly θ-pre-I-continuous functions and to obtain some properties of this new notion.