Perhaps you should try some spelling variations:
"modified rough approximation algorithm" » "modified rough approximation algorithms", "modified rough approximations algorithm", "modified one approximation algorithm"
"modified objective optimisation algorithm" » "modified objective optimization algorithm", "modified multiobjective optimization algorithm", "modified objective optimization algorithms", "modified objective estimation algorithm", "modified objective estimation algorithms"

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• If you are trying to use Boolean operators, they must be ALL CAPS: (("modified rough approximation algorithm") OR ("modified objective optimisation algorithm"))~.
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