Perhaps you should try some spelling variations:
"modified lighting approximation algorithms" » "modified diophantine approximation algorithms", "modified caging approximation algorithms"
"defined network optimization algorithm" » "defined network optimization algorithms", "defined network optimisation algorithm", "defined network estimation 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: "((\"modified lighting approximation algorithms\") OR (\"defined network optimization algorithm\"))~".
• Removing quotes may allow a broader search: (( modified lighting approximation algorithms ) OR ( defined network optimization algorithm ))~.
• Adding a wildcard symbol may retrieve word variants: (("modified lighting approximation algorithms") OR ("defined network optimization algorithm"))*.