Perhaps you should try some spelling variations:
surface expression » surface erosion
informative role » informative rule, information role, normative role
role surface » core surface, bone surface, love surface
array string » array strong, arrays strings, array sharing
array arcing » array forming, array probing, array sharing

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: informative role surface expression ((array string) OR (((array arcing) OR (array format))))~.
• Adding a wildcard symbol may retrieve word variants: informative role surface expression ((array string) or (((array arcing) or (array format))))*.