Modes of Convergence for Term Graph Rewriting

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Term graph rewriting provides a simple mechanism to finitely represent restricted forms of infinitary term rewriting. The correspondence between infinitary term rewriting and term graph rewriting has been studied to some extent. However, this endeavour is impaired by the lack of an appropriate counterpart of infinitary rewriting on the side of term graphs. We aim to fill this gap by devising two modes of convergence based on a partial order resp. a metric on term graphs. The thus obtained structures generalise corresponding modes of convergence that are usually studied in infinitary term rewriting. We argue that this yields a common framework in which both term rewriting and term graph rewriting can be studied. In order to substantiate our claim, we compare convergence on term graphs and on terms. In particular, we show that the resulting infinitary calculi of term graph rewriting exhibit the same correspondence as we know it from term rewriting: Convergence via the partial order is a conservative extension of the metric convergence.
Original languageUndefined/Unknown
Title of host publication22nd International Conference on Rewriting Techniques and Applications (RTA'11)
EditorsManfred Schmidt-Schau
Number of pages16
Place of PublicationDagstuhl, Germany
PublisherSchloss Dagstuhl--Leibniz-Zentrum für Informatik
Publication date1 May 2011
ISBN (Print)978-3-939897-30-9
Publication statusPublished - 1 May 2011

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