This note is concerned with a result about spines of manifolds embedded in a sphere, which proved useful at one point in (2).

We refer the reader to the IHES notes of Zeeman (14) for basic facts about PL (or piecewise-linear) manifolds. If Mm is a locally flat PL-submanifold of Qm+2, our object will be to study the normal structure of M in Q: one of our main results is:

There exists a PL-bundle over M, with fibre a 2-simplex, which is PL-homeomorphic to a neighbourhood of M in Q; moreover, the bundle and homeomorphism are unique up to equivalence. We also make an application to smoothing theory.

Introduction. We recall (see Morgan Ward (3), Birkhoff (1), p. 49) that a closure operator on a complete lattice ℒ is a mapping f from ℒ into ℒ satisfying the conditions

for all X, Y ∈ ℒ. The set of all closure operators on ℒ is itself a complete lattice with respect to the partial ordering in which f1 ≤ f2 if and only if f1(X) ≥ f2(X) for all X ∈ ℒ for every subset ℱ of and every element X ∈ ℒ we have

.

We extend certain results of the theory of closed operators in Banach spaces to general linear operators in normed spaces. A ‘state diagram’ for linear operators is drawn up. We prove some perturbation theorems, improving or correcting certain results of Goldberg.

Introduction. Let h*(X, A) be an extraordinary cohomology theory defined on the category of finite CW-pairs, that is, a cohomology theory satisfying all the axioms of Eilenberg and Steenrod (7) except the dimension axiom. This paper has three objects: to define and investigate the properties of the associated mod p cohomology theory h*(X, A; Zp) (see also (9)), to show that (with certain restrictions) if h*(X, A) is a multiplicative cohomology theory, so is h*(X, A. Zp), and lastly to generalize the notion of Bockstein coboundary homomorphisms and the apparatus of the Bockstein spectral sequence (see (4)) to an extraordinary cohomology theory.

Introduction. For applications in differential topology it is desirable to be able to find restrictions on the possible real and complex vector bundles over a given manifold. These restrictions usually state that the top component of some specific rational multinomial in the various characteristic classes is an integral multiple of the fundamental cocycle. For example, in proving non-embedding or non-immersion theorems (compare (1); (10)) one could test whether the normal bundle is consistent with these integrality conditions.

Introduction. The object of this paper is to obtain an explicit formula for the zeta function of an arbitrary non-singular cubic surface over a finite field. Let k denote the finite field of q elements, and kn the field of qn elements which is the unique algebraic extension of k of degree n. Let be a non-singular variety defined over k, and for each n > 0 let be the number of points defined over kn which lie on . The zeta function of is given by

Dwork has shown in (3) that for any this is a rational function of q−s; and in particular it follows from the results he proves in (4) that if is a non-singular cubic surface then

and hence also

Here the numbers w o depend only on q and on .

Introduction. Let Xi (i= 1, 2, 3,…) be a sequence of independent and identically distributed random variables with law ℒ(X) and write The Kolmogorov-Marcinkiewicz strong law of large numbers (Loève(6), p. 243) has the following statement:

If E|X|r < ∞, then with cr = 0 or EX according as r 1 or r ≥ 1.

Let R be the field of rational numbers, {x} = {x1, z2, …}, {y} = {y1, y2, …} be two countably infinite sets of variables and t an indeterminate. Let (λ) = (λ1, λ2, …, λm) be a partition of n. Then Littlewood (5) has shown that

can be expressed in the form

where Qλ(x, t) and Qλ(y, t) denote certain symmetric functions on the sets {x} and {y} respectively. In addition

where is the partition of n conjugate to (λ). In fact, Littlewood (5) showed that

where the summation is over all terms obtained by permutations of the variables xi (i = 1, 2, …) and

.

Introduction. In the classical Waring's problem, the following asymptotic formula was established by Vinogradov (see Vinogradov (2), Chapter VII).

If A = (am, n) is a regular matrix, then for any sequence x = {xn}, Am(x) will denote the transform and A-lim x denotes if that limit exists. We shall denote by the set of bounded sequences which are summed by A. If B is another regular matrix with then we say that B is b-stronger than A. In that case B must be b-consistent with A (see (4) and (6)), i.e. if then

If {μn} is a sequence of positive real numbers with we say that A and B are (μn)-consistent if every sequencer x = {xn} satisfying xn = 0(μn) which is summed by both A and B is summed to the same value by both matrices. A finite set of matrices A1, A2, …, AN is said to be simultaneously (μn)-inconsistent (b-consistent) if whenever is summed by Ai with (i = l, 2, …, N) then implies that The set of sequences, is denoted by

Definition. Let {sn} be the n-th partial sum of a given infinite series. If the transformation

where

is a sequence of bounded variation, we say that εanis summable |C, α|.

Introduction. In a recent paper, Borwein(1) constructed a new method of summability which would read: Let

and let {sn} be any sequence of numbers. If, for λ > − 1,

is convergent for all x in the open interval (0,1) and tends to a finite limit s as x → 1 in (0,1), we say that the sequence {sn} is Aλ convergent to s and write sn → s(Aλ). The A0 method is the ordinary Abel method.

Definition A. Let 0 < λ0 < λ1 < λ2 < …, λn → ∞ and suppose thatis a given infinite series write

where λm ≤ ω > λm+1. Also write for k > 0,

.

Introduction. The integral operators we shall be concerned with can be described with the help of the following:

Definition. A function F(u, v) will be called a primitive, if it is defined on the square 0 ≥ u, v ≥ 1, and satisfies the conditions (i) F(u, v) = 0 if u ≥ v; (ii) F(u, v) is a.c. (absolutely continuous) in each variable; (iii) there is a function p ∈ L(0, 1) such that |F1(u, v)| ≤ p(u), |F2(u, v)| ≤ p(v)a.e. (almost everywhere) on the square, where F1(u, v), F2(u, v) denote the partial derivatives of F(u, v) with respect to u, v respectively. It is not difficult to see that conditions (ii), (iii) imply that F(u, v) is a.c. in each variable uniformly with respect to the other variable or, as we say, is equi-a.c. in each variable. Thus, in the above definition, condition (iii) can be replaced by (iii), there is a p ∈ L(0, 1) such that for each v ∈ [0, 1], |F1(u, v)| ≤ p(u) a.e. in [0, 1] and for each v ∈ [0, 1], |F2(u, v)| ≤ p(u)a.e. in [0, 1].

In some problems where sine, cosine or Bessel functions are involved (e.g. (l), p. 35 et seq.), one has to satisfy certain initial conditions so that one obtains relations of the type

where t is a real parameter such that |t| < 1, and ±αn(n = 1, 2, …) are real simple zeros of an even or odd integral function f(z), being z = x + iy. An's are coefficients to be determined and, of course, ±ω is a real number that is not a zero of f(z).

Methods are developed for the computation of the complex zeros of (½z)−νJν(z) when the index ν is an arbitrary complex number. These methods, which do not require an explicit knowledge of the Jv(z), are susceptible to rapid numerical evaluation on a computer. Beyond the interest in the zeros in their own right, these methods now make feasible the use of the infinite product representation of Jν(z) for the rapid computation of Bessel functions of complex order.

In this paper we investigate certain generalized forms of third and fourth order non-homogeneous differential equations. Ezeilo (l) derived interesting results for the problem

.

We show similar results for:

,

and

.

An integral transformation is denned over a finite interval of the time domain. When the Laplace transform exists, the finite transform yields identical results. However, the finite transform is found to be considerably more general than the Laplace transform. It permits consideration of functions which are not of exponential order, leads to a simple scheme to determine system response, and is applicable to boundary-value problems.