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Light paths with an odd number of vertices in polyhedral maps
Authors:S. Jendroľ  H. J. Voss
Affiliation:(1) Department of Geometry and Algebra, P. J. "Scaron"afárik University and Institute of Mathematics, Slovak Academy of Sciences, Jesenná 5, 041 54 Ko"scaron"ice, Slovakia.;(2) Department of Algebra, Technical University Dresden, Mommsenstrasse 13, D-01062 Dresden, Germany.
Abstract:Let Pk be a path on k vertices. In an earlier paper we have proved that each polyhedral map G on any compact 2-manifold 
$$M$$
with Euler characteristic 
$$xleft( M right) leqslant {text{0}}$$
contains a path Pk such that each vertex of this path has, in G, degree 
$$leqslant kleft[ {frac{{5 + sqrt {49 - 24 times left( M right)} }}{2}} right]$$
. Moreover, this bound is attained for k = 1 or k ge 2, k even. In this paper we prove that for each odd 
$$k geqslant frac{{text{4}}}{{text{3}}}left[ {frac{{5 + sqrt {49 - 24 times left( M right)} }}{2}} right] + 1$$
, this bound is the best possible on infinitely many compact 2-manifolds, but on infinitely many other compact 2-manifolds the upper bound can be lowered to 
$$left[ {left( {k - frac{{text{1}}}{{text{3}}}} right)frac{{5 + sqrt {49 - 24 times left( M right)} }}{2}} right]$$
.
Keywords:graphs  path  polyhedral map  embeddings
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