Perhaps you should try some spelling variations:
communications conversation » communication conversation, communications convention, communications cooperation
conversation based » conversion based, conversation basic, conversation made
based extraction » based interaction, phase extraction, based education
range spaces » gauge spaces, range states, large spaces
large sparse » large scale
use spaces » tuple spaces, phase spaces, gauge spaces

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

• Performing a fuzzy search may retrieve terms with similar spellings: communications conversation based extraction ((((range spaces) or (use spaces))) or (large sparse))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: communications conversation based extraction ((((range spaces) OR (use spaces))) OR (large sparse)).
• Adding a wildcard symbol may retrieve word variants: communications conversation based extraction ((((range spaces) or (use spaces))) or (large sparse))*.