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

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: "((\"modified adaptive approximation algorithms\") OR (\"defined network optimization algorithms\"))~".
• Removing quotes may allow a broader search: (( modified adaptive approximation algorithms ) OR ( defined network optimization algorithms ))~.
• Adding a wildcard symbol may retrieve word variants: (("modified adaptive approximation algorithms") OR ("defined network optimization algorithms"))*.