Perhaps you should try some spelling variations:
"modified parameters estimation algorithms" » "modified parameter estimation algorithms", "modified parameter estimates algorithms", "modified parameter optimization algorithms", "modified parameters estimation algorithm", "modified parameters optimization algorithms", "modified parameters optimisation algorithm"
"modified policy approximation algorithms" » "modified complexity approximation algorithms", "modified one approximation algorithms", "modified time approximation algorithms"

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: (("modified policy approximation algorithms") OR ("modified parameters estimation algorithms"))~.
• Removing quotes may allow a broader search: (( modified policy approximation algorithms ) or ( modified parameters estimation algorithms ))~.
• Adding a wildcard symbol may retrieve word variants: (("modified policy approximation algorithms") or ("modified parameters estimation algorithms"))*.