Perhaps you should try some spelling variations:
"modified notion optimisation algorithm" » "modified notion optimization algorithms", "modified notion estimation algorithm", "modified notion estimation algorithms", "modified network optimization algorithm"
"modified time approximation algorithms" » "modified one approximation algorithms", "modified _ approximation algorithms", "modified bi1 approximation algorithms", "modified male 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 time approximation algorithms") OR ("modified notion optimisation algorithm"))~.
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