A weighting
w of the edges of a graph
G induces a colouring of the vertices of
G where the colour of vertex
v, denoted
cv, is
$
{\sum\nolimits_{e \mathrel\backepsilon v} {w{\left( e \right)}} }
$
{\sum\nolimits_{e \mathrel\backepsilon v} {w{\left( e \right)}} }
. We show that the edges of every graph that does not contain a component isomorphic to
K2 can be weighted from the set {1, . . . ,30} such that in the resulting vertex-colouring of
G, for every edge (
u,v) of
G,
cu ≠
cv.
Mathematics Subject Classification (2000): 05C15