منابع مشابه
New results on ptolemaic graphs
In this paper, we analyze ptolemaic graphs for its properties as chordal graphs. Firstly, two characterizations of ptolemaic graphs are proved. The first one is based on the reduced clique graph, a structure that was defined by Habib and Stacho [8]. In the second one, we simplify the characterization presented by Uehara and Uno [13] with a new proof. Then, known subclasses of ptolemaic graphs a...
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This paper discusses a new family of bounds for use in similarity search, related to those used in metric indexing, but based on Ptolemy’s inequality, rather than the metric axioms. Ptolemy’s inequality holds for the well-known Euclidean distance, but is also shown here to hold for quadratic form metrics in general. In addition, the square root of any metric is Ptolemaic, which means that the p...
متن کاملLongest Path Problems on Ptolemaic Graphs
SUMMARY Longest path problem is a problem for finding a longest path in a given graph. While the graph classes in which the Hamiltonian path problem can be solved efficiently are widely investigated, there are few known graph classes such that the longest path problem can be solved efficiently. Polynomial time algorithms for finding a longest cycle and a longest path in a Ptolemaic graph are pr...
متن کاملDigital Restoration of Ancient Papyri
Image processing can be used for digital restoration of ancient papyri, that is, for a restoration performed on their digital images. The digital manipulation allows reducing the background signals and enhancing the readability of texts. In the case of very old and damaged documents, this is fundamental for identification of the patterns of letters. Some examples of restoration, obtained with a...
متن کاملProbe Ptolemaic Graphs
Given a class of graphs, G, a graph G is a probe graph of G if its vertices can be partitioned into two sets, P (the probes) and N (the nonprobes), where N is an independent set, such that G can be embedded into a graph of G by adding edges between certain nonprobes. In this paper we study the probe graphs of ptolemaic graphs when the partition of vertices is unknown. We present some characteri...
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ژورنال
عنوان ژورنال: Archiv für Papyrusforschung und verwandte Gebiete
سال: 2002
ISSN: 0066-6459,1867-1551
DOI: 10.1515/apf.2002.48.1.98