Perhaps you should try some spelling variations:
"coder coder large open problems" » "coder coder large on problems" (Expand search), "coder decoder large open problems" (Expand search), "code code large open problems" (Expand search), "decoder codec large open problems" (Expand search), "coder under large open problems" (Expand search), "coder over large open problems" (Expand search), "coder order large open problems" (Expand search)
"_ python python python programming" » "_ pythons python python programming" (Expand search), "_ piton python python programming" (Expand search), "_ pitons python python programming" (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: (("coder coder large open problems") OR ("_ python python python programming"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"coder coder large open problems\") OR (\"_ python python python programming\"))".
• Removing quotes may allow a broader search: (( coder coder large open problems ) OR ( _ python python python programming )).
• Adding a wildcard symbol may retrieve word variants: (("coder coder large open problems") OR ("_ python python python programming"))*.