Perhaps you should try some spelling variations:
"defined network optimization algorithm" » "defined network optimization algorithms", "defined network optimisation algorithm", "defined network estimation algorithm"
"modified one approximation algorithms" » "modified time approximation algorithms", "modified _ approximation algorithms", "modified rough approximations algorithms", "modified male approximation algorithms", "modified near approximation algorithms", "modified orca approximation algorithms"

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("modified one approximation algorithms") or ("defined network optimization algorithm"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("modified one approximation algorithms") OR ("defined network optimization algorithm")).
• Removing quotes may allow a broader search: (( modified one approximation algorithms ) or ( defined network optimization algorithm )).
• Adding a wildcard symbol may retrieve word variants: (("modified one approximation algorithms") or ("defined network optimization algorithm"))*.