The group Am of automophisms of a one-rooted m-ary tree admits a diagonal monomorphism which we denote by x. Let A be an abelian state-closed (or self-similar) subgroup of Am. We prove that the recurrence and tree-topological closure A∗ of A is additively a finitely presented Zm [[x]]module where Zm is the ring of m-adic integers. Moreover, if A∗ is torsion-free then it is a finitely generated ...

An extensive genetic and physiological analysis of the cheetah by O'Brien et al. (1983; 1985; 1987) indicated that the cheetah showed monomorphism at the major histocompatability complex. This led O'Brien (1985) to propose that the cheetah suffered from an immunodeficiency and was highly susceptible to diseases. It was therefore decided to investigate cell-mediated and humoral immune responses ...

Motivated by relatively recent empirical studies on Schistosoma mansoni, we use a mathematical model to investigate the impacts of drug treatment of the definitive human host and coinfection of the intermediate snail host by multiple parasite strains on the evolution of parasites' drug resistance. Through the examination of evolutionarily stable strategies (ESS) of parasites, our study suggests...

Let X,Y be finite sets, r,s,h,??N with s?r,X?Y. By ?Xh we mean the collection of all h-subsets X where each subset occurs ? times. A coloring (partition) is r-regular if element in exactly r subsets color. one-regular color class a perfect matching. We are interested necessary and sufficient conditions under which an can embedded into s-regular ?Yh. Using algebraic techniques involving glueing ...