It is well-known that warped products play some important roles in differential geometry as well as in physics. In this article we extend the notion of warped product to the notion of convolution of Riemannian manifolds. We study the basic properties of convolutions of Riemannian manifolds. We also apply the notion of convolution to establish and characterise the Euclidean version of Segre embedding.

The term “rigid set” appears often in the literature in different contexts and with different meanings. In many cases the notions are unrelated, while in other they refer to related facts. Here we study infinite sets which are rigid according to [2] and analyse the relationship with the notion of rigidity used in [1]. We make several remarks, summarise different results in the area and prove a few new results.

A charactersiation of topologically weak mixing is given by using the topological sequence entropy.

In this paper we prove the existence of solutions to an inverse semilinear elliptic partial differential equation. Physically, solutions represent stream functions of steady planar flows with bounded vortices. The kinetic energy functional is maximised over the set of rearrangements of a given function.

Some conditions under which a derivation on some operator algebras can be completely determined by the action on operators of zero product are given.

We study the behaviour of the hitting probabilities of conditional Brownian motion in a domain D in Euclidean space when we apply polarization to D. We also study how polarization affects the probability that conditional Brownian motion meets a subset of D.

We introduce a concept of metric space valued mappings of two variables with finite total variation and define a counterpart of the Hardy space. Then we establish the following Helly type selection principle for mappings of two variables: Let X be a metric space and a commutative additive semigroup whose metric is translation invariant. Then an infinite pointwise precompact family of X-valued mappings on the closed rectangle of the plane, which is of uniformly bounded total variation, contains a pointwise convergent sequence whose limit is a mapping with finite total variation.

We study the weighted Turán type inequality for generalised Jacobi weights, and give a complete positive answer to Zhou's conjecture.

Let Mn be a nonpositively curved complete simply connected manifold and D ⊂ Mn be a convex compact subset with non-empty interior and smooth boundary. It is shown that the total mean curvature ∂D can be estimated in terms of volume and curvature bound.

Certain norm related functions of linear operators are considered in the very general setting of linear relations in normed spaces. These are shown to be closely related to the theory of strictly singular, strictly cosingular, F+ and F− linear relations. Applications to perturbation theory follow.

We perform a Gramian analysis of a frame multiresolution analysis to give a condition for it to admit a minimal wavelet set and to show that the frame bounds of the natural generator for the wavelet space of a degenerate frame multiresolution analysis shrink.

Jacobi-like forms are certain formal power series which generalise Jacobi forms in some sense, and they are closely linked to modular forms when their coefficients are holomorphic functions on the Poincaré upper half plane. We construct two types of vector bundles whose fibres are isomorphic to the space of certain formal power series and whose sections can be identified with Jacobi-like forms for a discrete subgroup of SL (2,ℝ).

A Banach space has the Radon–Nikodym Property if and only if every continuous weak* lower semi–continuous gauge on the dual space has a point of its domain where its subdifferential is contained in the natural embedding.

In this paper, we establish a Farkas-Minkowski type alternative theorem under the assumption of nearly semiconvexlike set-valued maps. Based on the alternative theorem and some other lemmas, we establish necessary optimality conditions for set-valued vector optimisation problems with extended inequality constraints in a sense of weak E-minimisers.

In this paper, we consider the growth of meromorphic solutions of nonlinear differential equations of the form L (f) + P (z, f) = h (z), where L (f) denotes a linear differential polynomial in f, P (z, f) is a polynomial in f, both with small meromorphic coefficients, and h (z) is a meromorphic function. Specialising to L (f) − p (z) fn = h (z), where p (z) is a small meromorphic function, we consider the uniqueness of meromorphic solutions with few poles only. Our results complement earlier ones due to C.-C. Yang.

In this paper we describe when two Toeplitz operators Tf and Tg on the Bergman space of the bidisc commute, where f = f1 + 2, g = g1 + ḡ2, fi, gi ∈ H∞(D2)(i = 1, 2).