Perhaps you should try some spelling variations:
complexity approximation » complex approximation, complexity applications, completeness approximation
approximation based » approximation a
based extensions » based extension, base extension, brand extensions
array string » array strong, arrays strings, array sharing
array arcing » array forming, array probing, array sharing
array using » arrays using

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: complexity approximation based extensions ((array string) OR (((array using) OR (array arcing))))~.
• Adding a wildcard symbol may retrieve word variants: complexity approximation based extensions ((array string) or (((array using) or (array arcing))))*.