AMBIGUITY AND HYPERGRAPHS

After a short review of the state of the arf about ambiguities a mathe matical formalization of some types of structural ambiguities is offer ed via graphs. The dependency frees can be arranged as hypergraphs, wi th nodes linked by several arcs. The various ambiguities are divided i nto two families, producing hypergraphs without cycles or with them, r espectively. For this second family the name of gravitational ambiguit y is proposed.