On a paper by Christofides et al. for solving the multiple-resource constrained, single project scheduling problem

A revision was made of the Christofides, Alvarez-Valdez and Tamarit (CAT) procedure for solving the single project scheduling problem. A 9-activity counterexample problem was used to prove that the branching strategy that was originally implemented can generate nonoptimal solutions. The construction of additional precedence relations or delay arcs used in the original CAT procedure for delaying activities was proven to be highly restrictive.