Perhaps you should try some spelling variations:
"utilzed hierarchical optimization" » "utilzed hierarchical organization" (Expand Search), "utilzed hierarchical distillation" (Expand Search), "utilzed hierarchical mutation" (Expand Search), "multilevel hierarchical optimization" (Expand Search), "using hierarchical optimization" (Expand Search)
"utilized hierarchical optimization" » "utilized hierarchical organization" (Expand Search), "utilized hierarchical distillation" (Expand Search), "utilized hierarchical mutation" (Expand Search), "multilevel hierarchical optimization" (Expand Search), "inspired hierarchical optimization" (Expand Search)

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