Ascending and descending Morse complexes are defined by the critical points and integral lines of a scalar field f defined on a manifold M. They induce a subdivision of M into regions of uniform gradient flow, thus providing a compact description of the topology of M and of the behavior of f over M. We represent the ascending and descending Morse complexes of f as a graph, that we call the Morse incidence graph (MIG). We have defined a simplification operator on the graph-based representation, which is atomic and dimension-independent, and we compare this operator with a previous approach to the simplification of 3D Morse complexes based on the cancellation operator. We have developed a simplification algorithm based on a simplification operator, which operates on the MIG, and we show results from this implementation as well as comparisons with the cancellation operator in 3D.