# Planning and Scheduling with Uncertainty in the Steel Sector: A Review
## 4 Scheduling Solutions in Steel Sector Considering Uncertainty: Literature Review
Inside the upstream segment proposals, almost all of them (45/53) include the continuous casting process, while half of them (24/53) deal with the whole steelshop problem (steel making + refining + casting). There are a few approaches (5/53) that consider the combined scheduling of casting and hot strip mill processes. In terms of the uncertainty scheduling approach, there is a greater number of authors (37/59) who have proposed reactive scheduling solutions against a lesser number (24/59) who have studied and developed proactive scheduling approaches. However, proactive studies seem to be a more recent approach, starting on 2008 and growing in frequency during the following years, while reactive scheduling solutions are present during the whole period covered by this review. Only a few authors consider the possibility of combining both approaches in their works (hybrid approaches), such as [PERSON] et al. [53], [PERSON] et al. [17; 27] or [PERSON] et al. [41]. This can be explained by the focus in recent years on the application of metaheuristics and simulation solutions to reactive approaches (see Table 2) which could be motivated by the necessity of improving the solutions to be executed dynamically in real production environments. Table 2 presents the studies considered to be using a reactive approach. The solutions analyzed are mainly distributed between predictive reactive (26/37) and robust predictive reactive (8/37). \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**Approach**} & \multicolumn{3}{c}{**Technique**} \\ \cline{2-7}
**Reference** & **Completely** & **Predictive** & **Probictive** & **Robust** & **Dispatching** & **Heuristics** & **Metaheuristics** & **Multiagent** **and other** \\  & **Reactive** & **Reactive** & **Reactive** & **Simulation** & **F** & **A** & **AI** \\ \[PERSON] et al. 1998 [19] & X & & & & X & & & X \\ [PERSON] et al. 2004 [20] & & & X & & & & X \\ [PERSON] et al. 2004 [21] & & & X & & & & X \\ [PERSON] et al. 2004 [15] & X & & & & X & & X \\ [PERSON] and [PERSON] 2007 [22] & & & X & & X & & \\ [PERSON] et al. 2008 [23] & & X & & & X & & \\ [PERSON] and [PERSON] 2008 [25] & & & & & X & TS & \\ [PERSON] and [PERSON] 2009 [26] & & X & & & & X \\ [PERSON] and [PERSON] & & & X & & & GA & \\
2009 [27] & & & X & & X & GA & \\ [PERSON] et al. 2010 [29] & & & X & & & GA & \\ [PERSON] et al. 2010 [30] & & & X & & GA & \\ [PERSON] et al. 2011 [31] & & X & & X & & GA & \\ [PERSON] et al. 2011 [32] & & & & X & & & ACO & X \\ [PERSON] et al. 2011 [34] & & & & & & X & \\ [PERSON] et al. 2011 [35] & & & & & & X & \\ [PERSON] and [PERSON] 2012 [16] & X & & & & & X & \\ [PERSON] et al. 2012 [36] & & & & & & & GA & \\ [PERSON] and [PERSON] 2012 [37] & & & & & & X & \\ [PERSON] and [PERSON] 2013 [38] & & & & X & & X & X \\ [PERSON] et al. 2013 [40] & & & & & & X & TS & \\ [PERSON] 2013 [41] & & & & & X & & DE & \\ [PERSON] et al. 2014 [18] & & & & & & & DE & \\ [PERSON] et al. 2014 [43] & & & & & & X & PSO & \\ [PERSON] et al. 2015 [14] & & & & & & X & FOA & \\ [PERSON] et al. 2015 [46] & & & & & X & & & PSO \\ [PERSON] et al. 2015 [47] & X & & & & X & & & PSO \\ [PERSON] et al. 2016 [52] & & & & & X & & X & \\ [PERSON] et al. 2016 [53] & & & & & & X & & X \\ [PERSON] et al. 2016 [55] & & & & & & X & \\ [PERSON] et al. 2017 [57] & & & & & & & DE & \\ [PERSON] et al. 2017 [59] & & & & & & GA + VNS & & \\ [PERSON] et al. 2017 [61] & & & & & & & GA + VNS & \\ [PERSON] et al. 2017 [62] & & & & & & X & & \\ [PERSON] et al. 2017 (9) [63] & & & & & & & X \\ [PERSON] et al. 2017 [65] & & & & & & X & GA & \\ [PERSON] et al. 2018 [69] & & & & & & X & ABC & \\ [PERSON] et al. 2019 [72] & & & & & & MILP + DE & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Reactive scheduling models in steel production. The category with fewest studies corresponds to the completely reactive, which only contains three studies: [PERSON] et al.