Perhaps you should try some spelling variations:
approximation algorithm » approximation algorithms
optimization algorithms » optimisation algorithm, estimation algorithms, estimation algorithm
orca approximation » one approximation, _ approximation, time approximation
df optimization » _ optimization, qoe optimization, _ optimisation
modified df » modified _, modified adam, modified bi1

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

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