['Future', 'work', 'may', 'consider', 'investigating', 'whether', 'the', 'algorithm', 'would', 'be', 'as', 'successful', 'or', 'not', 'in', 'solving', 'variants', 'of', 'the', 'MPSP', 'that', 'include', 'more', 'operational', 'constraints', ',', 'such', 'as', 'variable', 'cut', '-', 'off', 'grade', ',', 'grade', 'blending', ',', 'and', 'stockpiling', ',', 'as', 'it', 'is', 'in', 'solving', 'the', '“', 'classical', '”', 'variant', 'considered', 'in', 'this', 'paper', '.']