  A modular application of the integration by fractional expansion (IBFE)
method for evaluating Feynman diagrams is extended to diagrams that contain
loop triangle subdiagrams in their geometry. The technique is based in the
replacement of this module or subdiagram by its corresponding multiregion
expansion (MRE), which in turn is obtained from Schwinger's parametric
representation of the diagram. The result is a topological reduction,
transforming the triangular loop into an equivalent vertex, which simplifies
the search for the MRE of the complete diagram. This procedure has important
advantages with respect to considering the parametric representation of the
whole diagram: the obtained MRE is reduced and the resulting hypergeometric
series tend to have smaller multiplicity.
