Perhaps you should try some spelling variations:
"modified multiobjective optimization algorithms" » "modified multiobjective optimisation algorithm", "modified multiobjective estimation algorithms", "modified multiobjective estimation algorithm"
"modified positive solutions algorithm" » "modified positive solution algorithm", "modified positive evolution algorithm", "modified positive evolutionary algorithm", "modified passive solutions algorithm", "modified adaptive solutions algorithm"

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• If you are trying to use Boolean operators, they must be ALL CAPS: (("modified positive solutions algorithm") OR ("modified multiobjective optimization algorithms"))~.
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