Perhaps you should try some spelling variations:
"complementar constrained problems" » "complementar contained problems" (Expand Search), "complementar constrained problemas" (Expand Search), "complementar constrained problema" (Expand Search), "complementar constrained problemass" (Expand Search)
"complementaridade constraints problem" » "complementaridade constraints problema" (Expand Search), "complementaridade constraints problemas" (Expand Search)

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: "((\"complementar constrained problems\") OR (\"complementaridade constraints problem\"))~".
• Removing quotes may allow a broader search: (( complementar constrained problems ) OR ( complementaridade constraints problem ))~.
• Adding a wildcard symbol may retrieve word variants: (("complementar constrained problems") OR ("complementaridade constraints problem"))*.