Incidence Matrix

a -1 -1 -1 0 0

b 1 0 0 0 0

c 0 0 1 -1 1

d 0 1 0 1 -1

E = {? a, b ?, ? a, d ?, ? a, c ?, ? c, d ?, ? d, c ? }

-1: edge starts at that vertex (it’s incident from the vertex)

1: edge ends at that vertex (it’s incident to the vertex)

0: edge does not involve the vertex.