Some comments on Chen et al. ‘Production scheduling optimization algorithm for the hot rolling processes’

In a recent paper, Chen et al. (2008) proposed a nonlinear programming model and a meta-heuristic approach for production scheduling of the hot rolling processes. In this note, we show that their model is flawed and that the model can be changed to a linear programming model. Cij is stated to be variables in Equation (1) in their model but it is given parameters. Constraints (9) should also be corrected as follows.