  In this paper, we will investigate a harmonic cycle (discrete harmonic form).
With a CW-complex, we can construct the combinatorial Laplacian operator. The
kernel of the operator is the harmonic space, the set of harmonic cycles, and
is isomorphic to its homology due to combinatorial Hodge theory. We will
introduce four concepts; cycletree, unicyclization, winding number map, and
standard harmonic cycle. A cycletree is the disjoint union of a spanning tree
and an edge on a given graph. A unicyclization consists of a graph and
information substituting for faces. Then, we will define the winding number map
and the standard harmonic cycle, and prove related properties. Finally, we will
show a relation between the winding number and the inner product with the
standard harmonic cycle. Then, we will see the standard harmonic cycle is
actually a harmonic cycle. In other words, we give a combinatorial
interpretation on a harmonic cycle.
