  To investigate the topological structure of planar polygon decomposition on
trapezoids, which is formed by height functions. We use the oriented Reeb graph
of the function with a marked vertex. We describe all possible optimal Reeb
graphs in the case of polygon in general position with one local minimum and
one local maximum. By optimal Reeb graph we mean Reeb graph, which cann't be
obtaned from other Reeb graph by subdivision of an edge or a leaf attaching. In
this case polygon is a triangle with triangle holes. Constructed Reeb graphs
give topological structures of trapezoid maps on two-connected polygon with six
vertexes and three-connected polygon with nine vertexes.
