“…The third baseline hard assumption that has explicitly been made quite often is that the batches of products inside the line are moved by the injection of new batches of products without any separation device among them [111] , [43] , [117] , [114] , [65] , which results in product contamination; also known as interfaces or transmix [117] , [87] , [50] , [75] , [83] , [72] , [69] , [68] , [115] , [88] , [129] , [106] , [91] , [77] , [21] , [80] , [60] , [28] , [64] , [104] , [71] , [138] , [65] , [93] . Due to the high reprocessing costs of certain interfaces, some sequences of products have been considered to be forbidden [121] , [114] , [120] , [75] , [72] , [82] , [88] , [106] , [129] , [91] , [80] , [71] , [93] . Nonetheless, for some of the research work, these volumes of contaminated products have been considered to be either minimized in the constraints of the sequence [110] , or not having relevance to the operation of the pipeline [64] .…”