Perhaps you should try some spelling variations:
"coder coder spanning subgraph problem" » "coder coder spanning subgraphs problem" (Expand search), "coder cohort spanning subgraph problem" (Expand search), "coder cooker scanning subgraph problem" (Expand search), "coder under scanning subgraph problem" (Expand search), "coder decoder spanning subgraph problem" (Expand search), "code code spanning subgraph problem" (Expand search), "decoder codec spanning subgraph 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 spanning subgraph problem") OR ("_ python python python programming"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"coder coder spanning subgraph problem\") OR (\"_ python python python programming\"))".
• Removing quotes may allow a broader search: (( coder coder spanning subgraph problem ) OR ( _ python python python programming )).
• Adding a wildcard symbol may retrieve word variants: (("coder coder spanning subgraph problem") OR ("_ python python python programming"))*.