We show that there are uncountably many countable homogeneous lattices. We give a discussion of which such lattices can be modular or distributive. The method applies to show that certain other classes of structures also have uncountably many homogeneous members.

The purpose of this article is two fold. First, we show how quasi-periodic solutions for theN-body problem can be constructed by variational methods. We illustrate this by constructing uncountably many quasi-periodic solutions for the fourand six-body problems with equal masses. Second, we show by examples that a system of N masses can possess infinitely many simple or multiple choreographic so...

Let K be the kernel of an epimorphism χ : G → Z, for G a finitely presented group. If K has uncountably many normal subgroups of finite index r, then K has uncountably many subgroups (not necessarily normal) of any finite index greater than r. In particular, this is the case whenever G is subgroup separable and K is nonfinitely generated. Assume that G has an abelian HNN base contained in K. If...

A Piatetski-Shapiro sequence with exponent $\alpha$ is a of integer parts $n^\alpha$ $(n = 1,2,\ldots)$ non-integral $\alpha > 0$. We let $\mathrm{PS}(\alpha)$ denote the set those terms. In this article, we study so that equation $ax + by cz$ has infinitely many pairwise distinct solutions $(x,y,z) \in \mathrm{PS}(\alpha)^3$, and give lower bound for its Hausdorff dimension. As corollary, find...

In his recent series of lectures, Prof. B. I. Plotkin discussed geometrical properties of the variety of associative K-algebras. In particular, he studied geometrically noetherian and logically noetherian algebras and, in this connection, he asked whether there exist uncountably many simple K-algebras with a fixed finite number of generators. We answer this question in the affirmative using bot...