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.

• The words AND, OR and NOT may confuse the search; try adding quotes: "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))))*.