Finite planar emulators for K4,5-4K2 and K1,2,2,2 and Fellows' Conjecture

  • Authors:
  • Yo'av Rieck;Yasushi Yamashita

  • Affiliations:
  • Department of Mathematical Sciences, University of Arkansas, Fayetteville, AR 72701, United States;Department of Information and Computer Sciences, Nara Women's University Kitauoya Nishimachi, Nara 630-8506, Japan

  • Venue:
  • European Journal of Combinatorics
  • Year:
  • 2010

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Abstract

In 1988 Fellows conjectured that if a finite, connected graph admits a finite planar emulator, then it admits a finite planar cover. We construct a finite planar emulator for K"4","5-4K"2. Archdeacon [Dan Archdeacon, Two graphs without planar covers, J. Graph Theory, 41 (4) (2002) 318-326] showed that K"4","5-4K"2 does not admit a finite planar cover; thus K"4","5-4K"2 provides a counterexample to Fellows' Conjecture. It is known that Negami's Planar Cover Conjecture is true if and only if K"1","2","2","2 admits no finite planar cover. We construct a finite planar emulator for K"1","2","2","2. The existence of a finite planar cover for K"1","2","2","2 is still open.