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

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"modified policy approximation algorithms\") OR (\"modified parameter estimation algorithm\"))~".
• Removing quotes may allow a broader search: (( modified policy approximation algorithms ) OR ( modified parameter estimation algorithm ))~.
• Adding a wildcard symbol may retrieve word variants: (("modified policy approximation algorithms") OR ("modified parameter estimation algorithm"))*.