A fuzzy graph is a pair , where
is a fuzzy set on a vertex
set
and
is a fuzzy relation
on
satisfying
|
(1)
|
for all
(Rosenfeld 1975). For an undirected fuzzy graph,
is also a symmetric relation.
The support, or underlying crisp graph, has vertex set and edge set
|
(2)
| |||
|
(3)
|
When both
and
take values only in
,
the fuzzy graph reduces to an ordinary graph.