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{\bf Attila Bern\'ath and Henning Bruhn}
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{\bf Degree Constrained Orientations in Countable Graphs }
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Degree constrained orientations are orientations of an (undirected) graph
where the in-degree function satisfies given lower and upper bounds.
For finite graphs Frank and Gy\'arf\'as (1976) gave a necessary and
sufficient condition for the existence of such an orientation. We
extend their result to countable graphs.
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