This is what is written in page 172 of the thesis -
"BIBLIOGRAPHY
P. H. Cubaud. “Evaluation of Parallel Programs Completion Time using Bilogic PERT Networks.” Tech. Rep. 91-7, EHEI, Ecole des Hautes Etudes en Informatique, 45, rue des Saints-Peres, 75006 Paris France, September 1991. In this article a bilogic extension of PERT networks (called BIPERT) is proposed as a suitable model for parallel programs. In a BIPERT network, ingoing and outgoing links may either be inclusive (IN) or exclusive (EX), thus allowing to represent amongst parallelism also conditional branches and alternative parallelism, but also dead ends (if a node spawns several inclusive outgoing links, which are collected later on in an exclusive ingoing). Graphs containing such dead constructs are prohibited and called unlegal. A network where all nodes are IN/IN or EX/EX types, belongs to the class of series_parallel graphs, where exact analytic solution techniques are feasible. All other networks are to be solved using simulation or approximation techniques. "