We define an invariant of a three manifold equipped with a flat bundle
with vanishing homology. The construction is based on Morse theory us
ing several Morse functions simultaneously and is regarded as a higher
loop analogue of various product operations in algebraic topology. Th
ere is a heuristic argument that this invariant is related to perturba
tive Chern-Simons Gauge theory by Axelrod-Singer, etc. There is also a
theorem which gives a relation of the construction to open string the
ory on the cotangent bundle.