Perhaps you should try some spelling variations:
"modified orca approximation algorithms" » "modified one approximation algorithms", "modified _ approximation algorithms", "modified time approximation algorithms"
"mapping learning method algorithm" » "machine learning method algorithm", "enabling learning method algorithm", "mapping learning mom algorithm", "mapping learning methods algorithm", "mapping graining methods algorithm", "mapping learning emotion algorithm"

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"mapping learning method algorithm\") OR (\"modified orca approximation algorithms\"))~".
• Removing quotes may allow a broader search: (( mapping learning method algorithm ) OR ( modified orca approximation algorithms ))~.
• Adding a wildcard symbol may retrieve word variants: (("mapping learning method algorithm") OR ("modified orca approximation algorithms"))*.