Volume 21, No. 2 (2011)

Articles

QUASI PERFECTLY CONTINUOUS FUNCTIONS AND THEIR FUNCTION SPACES

A new class of functions called ‘quasi perfectly continuous functions’ is introduced. Basic properties of quasi perfectly continuous functions are studied and their place in the hierarchy of variants of continuity, that already exist in the literature, is elaborated. The notion of quasi perfect continuity, in general is independent of continuity, but coincides with perfect continuity (Indian J. Pure Appl. Math. 15(3) (1984), 241-250), a sig-nificantly strong form of continuity, if the range space is regular.

A CARLEMAN'S INEQUALITY REFINEMENT NOTE

The aim of this note is to give an improvement of Carleman’s inequality. The proof is elementary and our new inequality refines results stated by Bicheng and Debnath [Some inequlities involving the constant e and an application to Carleman’s inequlity. J. Math. Anal. Appl. 223 (1998) 347–353], Xie and Zhong [A best approximation for constant e and an improvement to Hardy’s inequality J. Math. Anal. Appl. 252 (2000) 994–998.], Ping and Guozheng [A Strengthened Carleman’s inequality. J. Math. Anal. Appl. 240 (1999) 290–293] and Yang [On Carleman’s inequality J. Math. Anal. Appl. 253 (2001) 691–694].

ON A SUBCLASS OF ANALYTIC FUNCTIONS WITH NEGATIVE COEFFICIENTS ASSOCIATED TO AN INTEGRAL OPERATOR INVOLVING HURWITZ-LERCH ZETA FUNCTION

Making use of an integral operator involving the Hurwitz-Lerch zeta function, we introduce a new subclass of analytic functions Q^{*\alpha}_{s,b}(\delta,\beta) defined in the open unit disk and investigate its various characteristics. Further we obtain distortion bounds, extreme points and radii of close-to-convexity, starlikeness and convexity for functions belonging to the class Q^{*\alpha}_{s,b}(\delta,\beta).

A GENERAL DECOMPOSITION THEOREM FOR CLOSED FUNCTIONS

Quite recently, the present authors [16] have defined and investigated the notion of mg^*-closed sets as a modification of g-closed sets due to Levine [10]. In this paper, we introduce the notion of mg^*-closed function and obtain a general decomposition of closed functions in topological spaces.

ON SEMILLATICE-ORDERED SEMIGROUPS. A CONSTRUCTIVE POINT OF VIEW

Semilattice-ordered semigroup is an important algebraic structure. It is ordered semigroup under anti-order. Some basic properties of semillatice-ordered semigroups with apartness are given by constructive point of view. Let I and K be compatible, an ideal and an anti-ideal of semilattice-ordered semigroup S. Constructions of compatible congruence E(I) and anti-congruence Q(K) on S, generated by I and K respec-tively, are given. Besides, we construct compatible order and anti-order θT on factor-semigroup S/(E(I),Q(K)). Some basic properties of such constructed semigroups are given.

ON FUZZY BI-IDEALS AND FUZZY QUASI IDEALS IN Γ-SEMIGROUPS

The purpose of this paper is to investigate some properties of fuzzy ideals and fuzzy bi-ideals in Γ -semigroups and to introduce the notion of fuzzy quasi ideals in Γ -semigroups. Here, we also characterize regular and intra-regular Γ -semigroup in terms of fuzzy quasi ideals and fuzzy bi-ideals.

ON WEAKLY θ-PRE-I CONTINUOUS FUNCTIONS

In this paper, a strong form in ideal topological spaces of weak θ -pre continuity, called weak θ -pre-I continuity, is introduced. It is shown that weak θ -pre-I continuity is strictly weaker than strong θ -pre-I continuity and that it is between continuity and almost weak continuity. Also, additional properties of these functions are investigated.