Perhaps you should try some spelling variations:
"coder coder controller optimization problems" » "coder coder control optimization problems" (Expand search), "coder coder constrained optimization problems" (Expand search), "coder coder controlled fertilization problems" (Expand search), "coder mode controller optimization problems" (Expand search), "coder order controller optimization problems" (Expand search), "coder power controller optimization problems" (Expand search), "coder decoder controller optimization problems" (Expand search), "code code controller optimization problems" (Expand search), "decoder codec controller optimization 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 controller optimization problems") OR ("_ python python python programming"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"coder coder controller optimization problems\") OR (\"_ python python python programming\"))".
• Removing quotes may allow a broader search: (( coder coder controller optimization problems ) OR ( _ python python python programming )).
• Adding a wildcard symbol may retrieve word variants: (("coder coder controller optimization problems") OR ("_ python python python programming"))*.