Perhaps you should try some spelling variations:
estimation algorithms » estimation algorithm, optimization algorithms, optimisation algorithm
sphere approximation » average approximation, time approximation
one approximation » time approximation, _ approximation, rough approximations
game estimation » pose estimation, game optimization

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

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