  We introduce an interpolation between Euler integral and Laplace integral:
Euler-Laplace integral. We establish a combinatorial method of constructing a
basis of the rapid decay homology group associated to Euler-Laplace integral
with a nice intersection property. This construction yields a remarkable
expansion formula of cohomology intersection numbers in terms of GKZ
hypergeometric series. As an application, we obtain closed formulas of the
quadratic relations of Aomoto-Gelfand hypergeometric functions and their
confluent analogue in terms of bipartite graphs.
