Volume 20, No. 2 (2010)
Articles
COMMON FIXED POINT THEOREMS OF MEIR-KEELER TYPE FOR OCCASIONALLY WEAKLY COMPATIBLE MAPPINGS
ABDELKRIM ALIOUCHE(1), VALERIU POPA(2)
We prove common fixed point theorems of Meir-Keeler type for four mappings satisfying implicit relations in metric spaces using the concept of occasionally weakly compatible mappings which generalizes results of [1], [7], [11-17], [19], [21], [28], [34-40], [47-48] and [50].
INDICATRIX OF A FINSLER VECTOR BUNDLE
MIHAI ANASTASIEI(1), MANUELA GÎRŢU(2)
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
S. JAFARI(1), N. RAJESH(2)
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.
COMMON FIXED POINTS OF TWO MAPS IN COMPLETE G-METRIC SPACES
HAKAN KARAYILAN(1), MUSTAFA TELCI(2)
In this paper, we present some common fixed point theorems for contraction type and expansion type mappings in complete G- metric spaces.
ACCURATE BOUNDS FOR A CONVERGENCE TO GAMMA CONSTANT
CRISTINEL MORTICI
The aim of this paper is to improve the result of Negoi [ A zarter convergence to the constant of Euler Gaz. Matem. Ser. A 15 (1997) 111.113] about the convergence speed of a sequence convergent to Euler-Mascheroni constant.
A CARISTI SELECTION THEOREM FOR A MULTIFUNCTION SATISFYING AN IMPLICIT CONTRACTIVE CONDITION OF LATIF-BEG TYPE
VALERIU POPA
We prove a general Caristi selection theorem for a multifunction which satisfies an implicit contractive condition of Latif-Beg type, which generalize the result from [13, Theorem 2.1].
TORSEFORMING VECTOR FIELDS IN A 3-DIMENSIONAL PARA SASAKIAN MANIFOLD
D.G. PRAKASHA
The object of the present paper is to study a torseforming vector field in a 3-dimensional para-Sasakian manifold. Here we prove that the torseforming vector field in a 3-dimensional para-Sasakian manifold is a concircular vector field.
ON THE CURVATURE TENSOR FIELD ASSOCIATED TO HOMOGENEOUS METRICAL STRUCTURES ON T<sup>2</sup>M
ADRIAN SANDOVICI
The main goal of this paper is to compute the curvature tensor field of the geometrical model determined by the second order prolongation of a Riemannian space endowed with certain homogeneous structure.
SUPRA PRE-OPEN SETS AND SUPRA PRE-CONTINUITY ON TOPOLOGICAL SPACES
O. R. SAYED
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.
SEQUENCES THAT CONVERGE TO A GENERALIZATION OF IOACHIMESCU'S CONSTANT
ALINA SÎNTĂMĂRIAN
We consider a generalization of Ioachimescu's constant as the limit I(a; s) of a sequence depending on two parameters a ∈ (0,+∞) and s ∈ (0,1). The purpose of this paper is to give some sequences that converge quickly to I(a; s).
LIPSCHITZ ESTIMATES FOR MULTILINEAR COMMUTATOR OF SINGULAR INTEGRAL WITH VARIABLE CALDERÓN-ZYGMUND KERNEL
ZHIQIANG WANG(1), LANZHE LIU(2)
In this paper, we will study the continuity of a multilinear commutator generated by the singular integral with variable Calderón-Zygmund kernel and the functions bj, on Triebel-Lizorkin space, Hardy space and Herz-Hardy space, where the functions bj belong to the Lipschitz space Lipβ(Rn)
STRONGLY θ-PRE-I-CONTINUOUS FUNCTIONS
SAZIYE YUKSEL(1), TUGBA HAN SIMSEKLER(2), ZEHRA G. ERGUL(3), TAKASHI NOIRI(4)
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.