The function isBipartite determines if a given graph is bipartite. A graph is said to be bipartite if the vertices can be partitioned into two sets W and Y such that every edge has one vertex in W and the other in Y. Since a graph is bipartite if and only if its chromatic number is 2, we can check if a graph is bipartite by computing its chromatic number.
i1 : S = QQ[a..e]; |
i2 : t = graph {a*b,b*c,c*d,a*e} -- a tree (and thus, bipartite)
o2 = Graph{edges => {{a, b}, {b, c}, {c, d}, {a, e}}}
ring => S
vertices => {a, b, c, d, e}
o2 : Graph
|
i3 : c5 = cycle S -- 5-cycle (not bipartite)
o3 = Graph{edges => {{a, b}, {b, c}, {c, d}, {d, e}, {a, e}}}
ring => S
vertices => {a, b, c, d, e}
o3 : Graph
|
i4 : isBipartite t o4 = true |
i5 : isBipartite c5 o5 = false |
The object isBipartite is a method function.