Perhaps you should try some spelling variations:
approximation algorithm » approximation algorithms
estimation algorithms » estimation algorithm, optimization algorithms, optimisation algorithm
one approximation » time approximation, _ approximation, rough approximations
risk estimation » pose estimation
modified risk » modified bi1
modified one » modified male, modified near, modified orca

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 algorithm ) or ( modified risk estimation algorithms ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( modified one approximation algorithm ) OR ( modified risk estimation algorithms )).
• Adding a wildcard symbol may retrieve word variants: (( modified one approximation algorithm ) or ( modified risk estimation algorithms ))*.