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On the finiteness of the recursive chromatic number

✍ Scribed by William I. Gasarch; Andrew C.Y. Lee


Publisher
Elsevier Science
Year
1998
Tongue
English
Weight
559 KB
Volume
93
Category
Article
ISSN
0168-0072

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✦ Synopsis


A recursive graph is a graph whose vertex and edge sets are recursive.

A highly recursive graph is a recursive graph that also has the following property: one can recursively determine the neighbors of a vertex. Both of these have been studied in the literature. We consider an intermediary notion: Let A be a set. An A-recursive graph is a recursive graph that also has the following property: one can recursively-in-A determine the neighbors of a vertex. We show that, if A is r.e. and not recursive, then there exists A-recursive graphs that are 2-colorable but not recursively k-colorable for any k. This is false for highly-recursive graphs but true for recursive graphs. Hence A-recursive graphs are closer in spirit to recursive graphs than to highly recursive graphs.


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