Perhaps you should try some spelling variations:
"defined network approximation algorithm" » "defined network approximation algorithms"
"modified allocation optimization algorithm" » "modified allocation optimization algorithms", "modified allocation optimisation algorithm", "modified allocation estimation algorithm", "modified location optimization algorithm"

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("modified allocation optimization algorithm") OR ("defined network approximation algorithm"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"modified allocation optimization algorithm\") OR (\"defined network approximation algorithm\"))".
• Removing quotes may allow a broader search: (( modified allocation optimization algorithm ) OR ( defined network approximation algorithm )).
• Adding a wildcard symbol may retrieve word variants: (("modified allocation optimization algorithm") OR ("defined network approximation algorithm"))*.