Perhaps you should try some spelling variations:
optimization algorithm » optimization algorithms, optimisation algorithm, estimation algorithm
rough approximations » one approximation
rough approximation » one approximation
qoe optimization » game optimization, _ optimization, stage optimization

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( qoe optimization algorithm ) or ( ((rough approximation) OR (rough approximations)) algorithm ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( qoe optimization algorithm ) OR ( ((rough approximation) OR (rough approximations)) algorithm )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( qoe optimization algorithm ) or ( ((rough approximation) OR (rough approximations)) algorithm ))".
• Adding a wildcard symbol may retrieve word variants: (( qoe optimization algorithm ) or ( ((rough approximation) OR (rough approximations)) algorithm ))*.