Perhaps you should try some spelling variations:
"_ estimation algorithms" » "_ estimation algorithm", "_ optimization algorithms", "_ optimisation algorithm"
"_ optimized algorithm" » "_ optimized algorithms", "_ optimizer algorithms"
"time approximation algorithms" » "one approximation algorithms", "_ approximation algorithms"

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

• Performing a fuzzy search may retrieve terms with similar spellings: (((("_ estimation algorithms") or ("_ optimized algorithm"))) or ("time approximation algorithms"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("_ estimation algorithms") OR ("_ optimized algorithm"))) OR ("time approximation algorithms")).
• Removing quotes may allow a broader search: (((( _ estimation algorithms ) or ( _ optimized algorithm ))) or ( time approximation algorithms )).
• Adding a wildcard symbol may retrieve word variants: (((("_ estimation algorithms") or ("_ optimized algorithm"))) or ("time approximation algorithms"))*.