Let G be a finite group. It is proved that the localised Buinside ring Ωp(G) is of finite representation type if and only if for each p–perfect subgroup H of G, , where means the conjugacy class of K.

A quantitative version of a classical result of S.N. Bernstein concerning the divergence of Lagrange interpolation polynomials based on equidistant nodes is presented. The proof is motivated by the results of numerical computations.

We give conditions under which pointwise multiplication is a continuous bounded operation on kth order Sobolev-Orlicz spaces. This result is used to derive a sufficient condition under which the superposition operator is a continuous bounded operator on these spaces.

In the present note we study the question: “Under which general conditions do certain Boolean sums of linear operators satisfy Telyakovskiǐ-type estimates?” It is shown, in particular, that any sequence of linear algebraic polynomial operators satisfying a Timan-type inequality can be modified appropriately so as to obtain the corresponding upper bound of the Telyakovskiǐ-type. Several examples are included.

We study the following question: given any local formation of finite groups, do there exist maximal local subformations? An answer is given by providing a local definition of the intersection of all maximal local subformations.

The concept of invexity is extended to nondifferentiable functions. Characterisations of nonsmooth invexity are derived as well as results in unconstrained and constrained optimisation and duality. The principal analytic tool is the generalised gradient of Clarke for Lipschitz functions.

In 1969, Ligh proved that distributively generated (d-g) Boolean near-rings are rings, and hinted that some of the more complicated polynomial identities implying commutativity in rings may turn d-g near-rings into rings. In the present paper we investigate the following conditions: (1) xy = (xy)n(x, y); (2) xy = (yz)n (xy); (3) xy = ym (x, y)xn (x, y); (4) xy = xy n(x, y)x; (5) xy = xn(x, y)ym (x, y); finally prove that under appropriate additional hypotheses a d-g near-ring must be a commutative ring. Indeed the theorem proved here is a wide generalisation of many recently established results.

We show that a ruled surface of finite type in a Euclidean space is a cylinder on a curve of finite type or a helicoid in Euclidean 3-space.

Let S(G) be a Segal algebra on an infinite compact Abelian group G. We study the existence of many discontinuous translation invariant linear functionals on S(G). It is shown that if G/CG contains no finitely generated dense subgroups, then the dimension of the linear space of all translation invariant linear functionals on S(G) is greater than or equal to 2C and there exist 2C discontinuous translation invariant linear functionals on S(G), where c and CG denote the cardinal number of the continuum and the connected component of the identity in G, respectively.

It is shown that weakly compact sets of James quasi reflexive space have normal structure.

A number of nonoscillation criteria for the Emden-Fowler system

where a(t), b(t) > 0, r1, r2 > 0 and b(t)/a(t) is locally of bounded variation, are established employing energy function techniques. The results obtained here include many known nonoscillation theorems for the classical Emden-Fowler equations as special cases. We illustrate the results obtained with several examples.

An orbital integral formula is proven for the direct integral decomposition of an induced representation of a connected nilpotent Lie group. Previous work required simple connectivity. An explicit description of the spectral measure and spectral multiplicity function is derived in terms of orbital parameters. It is also proven that connected (but not necessarily simply connected) exponential solvable symmetric spaces are multiplicity free. Finally, the qualitative properties of the spectral multiplicity function are examined via several illuminating examples.

We study a certain linear fourth order differential operator and show the existence of solutions to corresponding nonlinear problems. It will be shown that a maximum principle holds and that under certain conditions the linear operator has a positive principal eigenvalue with corresponding positive eigenfunction.

In this paper, we study a nonlinear partial differential equation on a compact manifold;

where a > 1 is a constant, r is a positive constant, and H is a prescribed smooth function.

Kazdan and Warner showed that if λ1(g) < 0 and < 0, where is the mean of H, then there is a constant 0 < r0(H) ≤ ∞ such that one can solve this equation for 0 < r < r0(H), but not for r > r0(H). They also proved that if r0(H) = ∞, then H(x) ≤ 0 (≢0) for all x ∈ M. They conjectured that this necessary condition might be sufficient.

I show that this conjecture is right; that is, if H(x) ≤ 0 (≠ 0) for all x ∈ M, then r0(H) = ∞.

We study in this paper the relations existing between Joly's rectangular constant (µ) and the degree of asymmetry of Birkhoff-James's orthogonality relation (β). New bounds on the variation of µ in terms of β and estimation of the values taken by β in the case of uniformly convex Banach spaces are given.

It is proved that the product of two non-zero derivations of a prime C*-algebra is bounded only if both of them are bounded.

A generalisation of the notion of “sets of measure zero” for arbitrary Banach spaces is defined so that continuous convex functions are automatically Gateaux differentiable “almost everywhere”. It is then shown that this class of sets satisfies all the properties tht one expects of sets of measure zero. Moreover (in a certain large class of Banach spaces, at least) nonempty open sets are not of “measure zero”.

A coefficient estimate for powers of a class of Bazilevic functions obtained by M.M. Elhosh, is disproved and some sharp bounds are given.

We show that if (M, g) is a distinguishing space-time, then any distance homothetic map from (M, g) onto arbitrary space-time (M′, g′) is a homothetic map; in particular, every distance preserving map is an isometry.

Interior estimates are derived for the C2, µ-Hölder norm of the radius vector X ∈ C1, 1 (Ω) of a locally convex surface Σ in terms of the first fundamental form IΣ, the Gauss curvature K and the integral ∫ |H| dσ. Here H is the mean curvature of Σ. The coefficients gij of IΣ are assumed to belong to the Hölder class C2, µ (Ω) for some μ, 0 < μ < 1. A boundary condition is discussed which ensures an estimate for ∫ | H | dσ.