Perhaps you should try some spelling variations:
"modified one approximation algorithm" » "modified one approximation algorithms", "modified time approximation algorithm", "modified _ approximation algorithm", "modified rough approximations algorithm", "modified male approximation algorithm", "modified near approximation algorithm", "modified orca approximation algorithm"
"modified _ optimisation algorithm" » "modified _ optimization algorithms", "modified _ estimation algorithm", "modified _ estimation algorithms"

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• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"modified one approximation algorithm\") OR (\"modified _ optimisation algorithm\"))~".
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