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Further Information
The main purpose of the article under review is to relate topological and ergodic properties of algebraically defined transformations on compact subsets of the field of all rational \(p\)-adic numbers \(\mathbb{Q}_p\). The authors start from basic simple notions and develop the relevant topological and measure theoretic concepts in a highly illuminating way. At first they give an introduction to \(p\)-adic numbers. Then they introduce the concept of minimality of a continuous transformation \(T:X \to X\) on a topological space \(X\) which means that each orbit \(\partial(x) :=\{T^n(x)\}_{n=-\infty}^\infty\) is dense in \(X\). In order to define the necessary concepts from ergodic theory the authors build up a measure which turns out to be the Haar measure on the locally compact group \(\mathbb{Q}_p\); this measure, applied to a ball in \(\mathbb{Q}_p\), is the radius of this ball. The main results are proved in full detail and should be accessible to everyone with a mathematical education in basic analysis, algebra and number theory.