Let G be a locally compact Abelian group, and the set of bounded complex (regular countably-additive Borel) measures on G. It is well known that becomes a Banach space if the norm is defined by

the supremum being over all finite sets of disjoint Borel subsets of G.

Indices of the free logarithmetic correspond to bifurcating root-trees (cf.(4)), to Evans' non-associative numbers (3) and to Etherington's partitive numbers (2). The free commutative logarithmetic is the homomorph of f determined by the congruence relation P + Q ∼ Q + P. Formulæ for aδ and pα, i.e. the numbers of indices of of a given potency* δ and the number of indices of a given altitude α respectively, were given by Etherington (1), who also gave corresponding formulæ for commutative indices of . Other enumeration formulæ are contained in (5).

Let us denote by α the set of n real numbers α1, …, αn, and by ck(α) and hk(α) the elementary and complete symmetric functions of degree k in α1, …, αn, and by ck(α) and hk(α) the elementary and complete symmetric functions of degree k in αl, …, αn, i.e. ck(α) is the sum of all possible products of k different αi and hk(α) is the sum of all possible products of k αi, where now in any product one or more αi may be repeated any number of times.

Let T(α1, α2, …, αn−1) be the n-ary transformation which takes the sequence {si}, (i = 0, 1, …), into the sequence {s'i} where

with sm = 0 when m is a negative integer, and where α1, …, αn an are real numbers with sum unity. In a previous note (1) conditions were found on α and β for the ternary transformation T(α, β) to be equivalent to convergence. A method is given here for treating the similar problem for the general n-ary transformation.

A groupoid is a set closed with respect to a binary operation. It is commutative and entropic if xy = yx and xy.zw = xz.yw hold for all its elements. It is cyclic if it is generated by one element. Let x be the generator of the free commutative entropic cyclic groupoid . Then any element of can be written in the form xP where x1 = x and xQ+R = xQxR. Two indices P, Q are equal (called “concordant” in (3)) if and only if xP = xQ. The groupoid of these indices, the free additive commutative entropic logarithmetic (cf. (3)), is clearly isomorphic to .

Certain functions of infinite matrices are known to exist.† This gives rise to the following questions:

1. Whether the power series of matrices

has a zero in the field ‡ of infinite matrices, and

2. If f(A) exists for a certain infinite matrix A, is there an infinite matrix B such that

In other words, is there a matrix period for f(A)?

In this paper theorems concerning zeros and periodicity of functions of semi block infinite matrices § (defined below) are established.

Making use of properties of doubly-stochastic matrices, I recently gave a simple proof (4) of a theorem of Ky Fan (Theorem 2b below) on symmetric gauge functions. I now propose to show that the same idea can be employed to derive a whole series of results on convex functions ; in particular, certain well-known inequalities of Hardy-Littlewood-Pólya and of Pólya will emerge as specìal cases.

In the full linear theory of thermoelasticity there is a coupling between the thermal and the purely mechanical effects so that not only does a nonuniform distribution of temperature in the solid produce a state of stress but dynamical body forces or applied surface tractions produce variations in temperature throughout the body. In a recent paper (Eason and Sneddon, (2)) an account was given of the calculation of the dynamic stresses produced in elastic bodies, both infinite and semi-infinite, by uneven heating. In this paper we shall consider the propagation of thermal stresses in an infinite medium when, in addition to heat sources, there are present body forces which vary with the time.