If L is a distributive lattice in which every element is the join of finitely many join-irreducible elements, and if the set of join-irreducible elements of L satisfies the descending chain condition, then L satisfies the descending chain condition: this follows easily from the results of Chapter VIII, Section 2, in the Third (New) Edition of Garrett Birkhoff's ‘Lattice Theory’ (Amer. Math. Soc., Providence, 1967). Certain investigations (M. S. Brooks, R. A. Bryce, unpublished) on the lattice of all subvarieties of some variety of algebraic systems require a similar result without the assumption of distributivity. Such a lattice is always join-continuous: that is, it is complete and (∧X) ∨ y = ∧ {x ∨ y: x ∈ X} whenever X is a chain in the lattice (for, the dual of such a lattice is complete and ‘algebraic’, in Birkhoff's terminology). The purpose of this note is to present the result:

The theory of discrete, abstract groups, as presented in current texts, consists of investigations of various special classes of groups: it has very few completely general results. For some classes (say, for finite groups) the investigations have been extensive and successful; in a few cases (say, for finitely generated abelian groups) they have even reached a sense of completeness. The choice of some of these classes was dictated by the needs of other branches of mathematics. Many more were introduced with the view of extending the scope of certain powerful but special results, and a large part of the literature is taken up by elaborate counterexamples which mark the limits of these generalizations. In so far as one is looking for some kind of classification theory, it is immediately evident that the classes investigated were chosen by historical accident rather than by any master plan, and so far do not appear to form the initial part of a pattern which could be enlarged and completed in the future.

Iseki and Kasahara (see [3]) have given a Hahn-Banach type theorem for semifield-valued linear functionals on real linear spaces. We shall generalize their result by considering linear spaces over semifields.

Consider the classical Hardy spaces Hp(T) (1 ≦ p ≦ ∞) on the unit circle T. We shall ignore completely the fact that the elements of Hp(T) can be extended via the Poisson formula to certain types of functions analytic inside the unit disc. For our purposes, Hp(T) is the closed ideal in Lp(T) consisting of those functions f ∈ Lp(T) for which (n) = 0 (n= –1, –2,…).

Let ε > 0 be a small real parameter, let y, z be real m-dimensional and n-dimensional vectors respectively and let f, g be respectively real m-dimensional and n-dimensional vector functions of their arguments. This paper aims to discuss the following two problems in singular perturbations.

In this paper we aim to give a characterization of the finite simple group L4(3) (i.e. PSL(4, 3)) by the structure of the centralizer of an involution contained in the centre of its Sylow 2-subgroup. More precisely, we shall prove the following result.

The aim of this paper is to give a characterization of the finite simple group U4(3) i.e. the 4-dimensional projective special unitary group over the field of 9 elements. More precisely, we shall prove the following result.

Throughout this note Rn denotes the n-dimensional Euclidean space. Addition and multiplication in Rn are defined component-wise. If k ≦ n is a positive integer and x ∈ Rn, we write xk for the k-th component of x. The set {x ∈ Rn: xk ≠ 0 for each k ≦ n} is designated by R#.

A result contained in a previous paper [1] of the author is Theorem 1. If (G, K, H) is a T3-triple, G is finite, a is an involution contained in G–N(K) and H ∩ Ka=1, then the factor group of G over its centre is isomorphic to a group of similarities over a finite field.

We here study permutational products of groups, a study which was initiated by B. H. Neumann [8], [9].

It is shown that Einstein's 1929 Unified Field Theory and that of Levi-Civita are incompatible.

An elementary, purely algebraic derivation of the most general Lorentz transformations without spacial rotation and of the Thomas precession is given.

If Φ is a real number with |Φ| ≧ 1, then a semiregular continuet fraction development of Φ is denoted by where the ai are integers such that |ai| ≧ 2. The expansions arise geo-. metrically by considering the sequence of divided cells of two-dimensional grids (see [1]), and are described by the following algorithm: for all n ≧ 0, taking Φ = Φ.0 Hence where in this case the square brackets are used to signify the integer-part function. It follows that each irrational Φ has uncountably many such expansions, none of which has a constantly equal to 2 (or -2) for large n.

In a recent paper [1] Adati and Miyazawa studied conformally recurrent spaces, that is, Riemannian spaces defined by where is the conformal curvature tensor: λi is a non-zero vector and comma denotes covariant differentiation with respect to the metric tensor gij.

Large finite groups have large automorphism groups [4]; infinite groups may, like the infinite cyclic group, have finite automorphism groups, but their endomorphism semigroups are infinite (see Baer [1, p. 530] or [2, p. 68]). We show in this paper that the corresponding propositions for semigroups are false.

K. W. Chang generalizing a result of Lazer [3], proved in [4] the following THEOREM 1. Suppose that f:I → R+ = (0, + ∞), I = ([t0, + ∞), t0 0, is a non-decreasing function whose derivatives of orders ≧ 3 exist are continuous on ([t0, + ∞). Moreover, limt→+∞f(t) = +∞ and for some α, 1≧ α ≧ 2, and F =f-1/α then every solution x(t) of the equation tends to zero as t - + ∞.

In this short note we shall apply the theory of semi-groups of operators, (cf: Hille and Phillips, [2]), to the problem of representing solutions of certain differential equations with non-constant coefficients. When the coefficients are constant, this representation reduces to the usual Laplace transform solution of the relevant equation.

Let K be an open convex domain in n-dimensional Euclidean space, symmetric about the origin O, and of finite Jordan content (volume) V. With K are associated n positive constants λ1, λ2,…,λn, the ‘successive minima of K’ and n linearly independent lattice points (points with integer coordinates) P1, P2, …, Pn (not necessarily unique) such that all lattice points in the body λ,K are linearly dependent on P1, P2, …, Pj-1. The points P1,…, Pj lie in λK provided that λ > λj. For j = 1 this means that λ1K contains no lattice point other than the origin. Obviously

In a paper by Polimeni [3] the concept of a c-group was introduced. A group is called a c-group if and only if every subnormal subgroup is characteristic. His paper claims to characterize finite soluble c-groups, which we will call fsc-groups. There are some errors in this paper; see the forthcoming review by K. W. Gruenberg in Mathematical Reviews.

For any point x, we use the symbol x to denote {(x, x)}. By a triform, we mean a triple (X, Fx, S[X]) where X is a nonempty set, Fx is a family of subsets of X, [X] is a family of subsets of X x X and the following conditions are satisfied: .