We investigate a homeomorphism problem on a class of self-similar sets called generalized Sierpiński carpets (or shortly GSCs). It follows from two well-known results by Hata and Whyburn that a connected GSC is homeomorphic to the standard Sierpiński carpet if and only if it has no local cut points. On the one hand, we show that to determine whether a given GSC is connected, it suffices to iterate the initial pattern twice. We also extend this result to higher dimensional cases and provide an effective method on how to draw the associated Hata graph which allows automatical detection by computer. On the other hand, we obtain a characterization of connected GSCs with local cut points. Toward this end, we first deal with connected GSCs with cut points and then return to the local problem. The former is achieved by dividing the collection of GSCs into two parts, i.e., fragile cases and non-fragile cases, and discussing them separately. An easilychecked necessary condition is presented in addition as a byproduct of the above discussion. Finally, we also look into the size of the associated digit sets and possible numbers of cut points of connected GSCs.
In this paper, we present an effective method to characterize completely when a disconnected fractal square has only finitely many connected components. Our method is to establish some graph structures on fractal squares to reveal the evolution of the connectedness during their geometric iterated construction. We also prove that every fractal square contains either finitely or uncountably many connected components. A few examples, including the construction of fractal squares with exactly m 2 connected components, are added in addition.
The notion of recurrent fractal interpolation functions (RFIFs) was introduced by Barnsley et al. [‘Recurrent iterated function systems’, Constr. Approx.5 (1989), 362–378]. Roughly speaking, the graph of an RFIF is the invariant set of a recurrent iterated function system on
$\mathbb {R}^2$
. We generalise the definition of RFIFs so that iterated functions in the recurrent system need not be contractive with respect to the first variable. We obtain the box dimensions of all self-affine RFIFs in this general setting.
In a previous work joint with Dai and Luo, we show that a connected generalized Sierpiński carpet (or shortly a GSC) has cut points if and only if the associated \(n\)-th Hata graph has a long tail for all \(n\ge 2\). In this paper, we extend the above result by showing that it suffices to check a finite number of those graphs to reach a conclusion. This criterion provides a truly "algorithmic" solution to the cut point problem of connected GSCs. We also construct for each \(m\ge 1\) a connected GSC with exactly \(m\) cut points and demonstrate that when \(m\ge 2\), such a GSC must be of the so-called non-fragile type.
In this paper, we introduce and prove several generalizations of the Radon inequality. The proofs in the current paper unify and also are simpler than those in early published work. Meanwhile, we find and show the mathematical equivalences among the Bernoulli inequality, the weighted AM-GM inequality, the Hölder inequality, the weighted power mean inequality and the Minkowski inequality. Finally, some applications involving the results proposed in this work are shown.2010 Mathematics Subject Classification. Primary: 26D15. Key words and phrases. The Bergström inequality, the Radon inequality, the weighted power mean inequality, equivalence, the Hölder inequality.Full paper.
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