Perhaps you should try some spelling variations:
"modified response approximation algorithm" » "modified one approximation algorithm", "modified response association algorithm"
"modified notion approximation algorithms" » "modified network approximation algorithms", "modified time approximation algorithms", "modified one approximation algorithms"

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