Perhaps you should try some spelling variations:
"coder precoder variable density problem" » "coder gender variable density problem" (Expand search), "coder precoder variable identity problem" (Expand search), "coder precoder variable density probes" (Expand search), "coder precoder variable diversity problem" (Expand search), "coder decoder variable density problem" (Expand search)
"api python python python programming" » "api pythons python python programming" (Expand search), "api piton python python programming" (Expand search), "api 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 precoder variable density problem") OR ("api python python python programming"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"coder precoder variable density problem\") OR (\"api python python python programming\"))".
• Removing quotes may allow a broader search: (( coder precoder variable density problem ) OR ( api python python python programming )).
• Adding a wildcard symbol may retrieve word variants: (("coder precoder variable density problem") OR ("api python python python programming"))*.