Perhaps you should try some spelling variations:
"improving discrete-valued functions" » "improving discrete-value functions" (Expand Search), "improving discrete-values functions" (Expand Search), "improving discrete-valued function" (Expand Search)
"promising discrete-valued functions" » "promising discrete-value functions" (Expand Search), "promising discrete-values functions" (Expand Search), "promising discrete-valued function" (Expand Search)

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("improving discrete-valued functions") OR ("promising discrete-valued functions"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"improving discrete-valued functions\") OR (\"promising discrete-valued functions\"))*".
• Removing quotes may allow a broader search: (( improving discrete-valued functions ) OR ( promising discrete-valued functions ))*.