Perhaps you should try some spelling variations:
"coder decoder array teaching problem" » "coder decoder array teaching program" (Expand search), "coder decoder array teaching profile" (Expand search), "coder decoder array teaching programs" (Expand search), "coder decoder array tracing problem" (Expand search), "coder decoder early teaching problem" (Expand search), "coder decoder play teaching problem" (Expand search), "encoder decoder array teaching problem" (Expand search), "coder diode array teaching problem" (Expand search)
"on python python python programming" » "on pythons python python programming" (Expand search), "on piton python python programming" (Expand search), "on pitons python python programming" (Expand search), "in python pythin python programming" (Expand search), "of python pythof python programming" (Expand search), "_ python pyth_ 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 decoder array teaching problem") OR ("on python python python programming"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"coder decoder array teaching problem\") OR (\"on python python python programming\"))".
• Removing quotes may allow a broader search: (( coder decoder array teaching problem ) OR ( on python python python programming )).
• Adding a wildcard symbol may retrieve word variants: (("coder decoder array teaching problem") OR ("on python python python programming"))*.