By a result of K.B. Lee, the lattice of varieties of pseudo-complemented distributive lattices is the ω + 1 chain

where B−1, B0, B1 are the varieties formed by all trivial, Boolean, and Stone algebras, respectively. General theorems on relative universality proved in the present paper imply that there is a proper class of non-isomorphic algebras in B3 with finite endomorphism monoids, while every infinite algebra from B2 has infinitely many endomorphisms. The variety B4 contains a proper class of non-isomorphic algebras with endomorphism monoids consisting of the identity and finitely many right zeros; on the other hand, any algebra in B3 with a finite endomorphism monoid of this type must be finite.

Let belong to the class of α-spiral functions of order ρ(|α| < π/2, 0 ≤ ρ < 1). In this paper, we determine sharp coefficient estimates for functions of the form f(z)t, where t is a positive integer. We also study the influence of the second coefficient on the other coefficients for such functions. The results obtained not only generalize the results of MacGregor, Boyd, Srivastava, Silverman and Silvia and others, but also give rise to new results.

A proof is given for the existence of at least one stable periodic limit cycle solution for the polynomial non-linear differential equation of the form

in some cases where the Levinson-Smith criteria are not directly applicable.

In this note we point out that a recent result of Leung concerning hypersurfaces of a Euclidean space has a simple generalisation to hypersurfaces of complete simply-connected Riemannian manifolds of non-positive constant sectional curvature.

The energy functional for a pendent drop in a capillary tube is neither convex nor bounded from below. We obtain local minima of the energy by making the physically reasonable assumption that the gravitation or the prescribed volume of the drop is small.

The classification of the finite simple groups has had far-reaching consequences for many branches of algebra. This paper is a discussion of several problems about primitive permutation groups which have been solved using the simple group classification.

In this paper we construct the prolongation of a linear connection Γ on a manifold Μ to the bundle space of its frame bundle, and show that such prolongated connection coincides with the so-called complete lift of Γ to .

The purpose of this paper is to introduce two new classes of locally convex spaces which contain the classes of semi-Montel and Montel spaces. Further we give some examples and study some properties of these classes. As to permanence properties, these classes have similar properties to semi-Montel and Montel spaces except strict inductive limits and these classes are not always preserved under their completions. We shall call these two classes as β–semi–Montel and β–Montel spaces. A β–semi–Montel space is obtained by replacing the word “bounded” by “strongly bounded” in the definition of a semi–Montel space. If a β–semi–Montel space is infra-barrelled, we call the space β–Montel.

In this paper we obtain some classical results by using the general integral operators which transform Jakubowski's class K(m, M) into itself and K(μ) × S(m, M) into K(μ). Our results generalize some recent known results due to Causey and Reade, Patil and Thakare.

We prove the local triviality of module bundles over semisimple Lie algebra bundles and using this result we establish the complete reducibility of module bundles over semisimple Lie algebra bundles.

This paper deals with approximation of certain operators defined on the space C(X) of real-valued continuous functions on an arbitrary compact metric space (X, d). In particular the problem of giving quantitative Korovkin type theorems for approximation by positive linear operators is solved. This is achieved by using a smoothing approach and the least concave majorant of the modulus of continuity of a function f in C(X). Several new estimates are given as applications, including such for Shepard's method of metric interpolation.

The authors determine the sharp radius of convexity for functions analytic in the unit disc having power series representation of the form f(z) = z + an+1zn+1 + an+2zn+2 + … where an+1 is fixed and such that zf′(z)/f(x) = (1 + Aw(z))/(1 + Bw(z)), −1 ≤ B < 0 < A ≤ 1 where w(z) is an analytic function satisfying the conditions of Schwarz's lemma, in the case A + B ≥ 0. The estimate obtained is an improvement over the corresponding result obtained by Mogra and Juneja for functions analytic and starlike in the unit disc, with missing coefficients where the initial non-vanishing coefficient is fixed.