“…PI has been defined from many perspectives, it has been classified in terms of approaches [27], categorized into different domains [28] and spanning across various scales [24]. As in process synthesis, the PI solution approaches are also classified in terms of a) heuristics or knowledge based [6,[29][30][31], b) mathematical optimization based [14,[17][18][19][32][33][34][35][36] and c) hybrid approaches [23][24][25][37][38][39][40]. So far, many definitions have been proposed for PI, yet none has been uniquely recognised.…”