Perhaps you should try some spelling variations:
"modified df approximation algorithm" » "modified df approximation algorithms", "modified _ approximation algorithm", "modified one approximation algorithm", "modified time approximation algorithm", "modified adam approximation algorithm", "modified bi1 approximation algorithm"
"modified notion optimization algorithms" » "modified notion optimisation algorithm", "modified notion estimation algorithms", "modified notion estimation algorithm", "modified network optimization algorithms", "modified policy optimization algorithms", "modified allocation optimization algorithms"

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("modified df approximation algorithm") OR ("modified notion optimization algorithms"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"modified df approximation algorithm\") OR (\"modified notion optimization algorithms\"))*".
• Removing quotes may allow a broader search: (( modified df approximation algorithm ) OR ( modified notion optimization algorithms ))*.