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

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

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