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

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

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