Perhaps you should try some spelling variations:
"modified notion approximation algorithms" » "modified network approximation algorithms", "modified time approximation algorithms", "modified one approximation algorithms"
"modified learning emotion algorithm" » "mobile learning emotion algorithm", "modified caging emotion algorithm", "modified learning evolution algorithm", "modified learning estimation algorithm", "modified learning predation algorithm", "modified learning method algorithm"

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• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"modified notion approximation algorithms\") OR (\"modified learning emotion algorithm\"))~".
• Removing quotes may allow a broader search: (( modified notion approximation algorithms ) OR ( modified learning emotion algorithm ))~.
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