List-Compactness of Infinite Directed Graphs |
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| Authors: | Bruce L. Bauslaugh |
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| Affiliation: | (1) Department of Mathematics and Statistics, University of Calgary, Calgary, Alberta, T2N 1N4, Canada. e-mail: bauslaug@math.ucalgary.ca, CA |
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| Abstract: | A digraph H is homomorphically compact if the digraphs G which admit homomorphisms to H are exactly the digraphs whose finite subdigraphs all admit homomorphisms to H. In this paper we define a similar notion of compactness for list-homomorphisms. We begin by showing that it is essentially only finite digraphs that are compact with respect to list-homomorphisms. We then explore the effects of restricting the types of list-assignments which are permitted, and obtain some richer characterizations. Received: May 16, 1997 Final version received: January 16, 1998 |
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