a classical result of neumann characterizes the groups in which each subgroup has finitely many conjugates only as central-by-finite groups. if x is a class of groups, a group g is said to have x-conjugate classes of subgroups if g/coreg(ng(h)) 2 x for each subgroup h of g. here we study groups which have soluble minimax conjugate classes of subgroups, giving a description in terms of g/z(g). w...

Abstract The present paper deals with uncertain linear optimization problems where the objective function coefficient vector belongs to a compact convex uncertainty set and feasible is described by semi-infinite inequality system (finitely many variables possibly infinitely constrainsts), whose coefficients are also uncertain. Perturbations of both, constraint set, measured Hausdorff metric. ma...

In this paper, we study the following class of fractional Choquard-type equations $$\begin{aligned} (-\Delta )^{1/2}u + u=\Big ( I_\mu *F(u)\Big )f(u), \quad x\in \mathbb {R}, \end{aligned}$$ where $$(-\Delta )^{1/2}$$ denotes 1/2-Laplacian operator, $$I_{\mu }$$ is Riesz potential with $$0<\mu <1$$ , and F primitive function f. We use variational methods minimax estimates to existence solution...

We consider the problem of estimating the scale parameter &beta of a rescaled F-distribution when &beta has a lower bounded constraint of the form &beta&gea, under the entropy loss function. An admissible minimax estimator of the scale parameter &beta, which is the pointwise limit of a sequence of Bayes estimators, is given. Also in the class of truncated linear estimators, the admissible estim...

We initiate the study of a duality theory which applies to norm inequalities for pointwise weighted geometric means positive operators. The finds its expression in terms certain factorisation properties function spaces are naturally associated inequality under consideration. relate our Maurey–Nikishin–Stein operators, and present fully multilinear version Maurey’s fundamental theorem on operato...

We introduce two kinds of risk measures with respect to some reference probability measure, which both allow for a certain order structure and domination property. Analyzing their relation each other leads the question when minimax inequality is actually an equality. then provide conditions under corresponding robust measures, being defined as supremum over all induced by set can be represented...