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