I know that the sentence "time flies like an arrow" could have lots of meaning and there is an ambiguity but I draw a tree and I got confused that which meaning is more suitable for this tree.




NP→ Det NN

NN→ time, flies, arrow

det→ an

v→ like

meaning 1)there exists a particular arrow x such that every time flies (a kind of insect) likes x.( many flies one arrow) meaning 2) for every every "time flies"(a kind of insect)y, there is an arrow x such that y likes x (many flies , one arrow per fly)

1 Answer 1


If you mean 'time flies' as you would mean 'fruit flies', then wouldn't 'time flies' have to be one NN, or 'time' to be a modifier? With your current phrase structure rules or lexicon you do not allow this interpretation. You'll have to add rules that either license a construction allowing 'time' to act as a modifier of 'flies', or change the lexicon.

  • Couldn't we say that Time is the name of the flies, then we need separate NN for that?
    – liza
    Commented Apr 23, 2016 at 19:22
  • would that not indicate that the two words are somewhat separate, rather than depending on each other's meaning? I suppose this raises the question, is Charles Dickens 1 NN or 2 NN? I would certainly say it is one - only one entity being described. Commented Apr 23, 2016 at 19:59
  • Why is the leaf node called 'NN' instead of 'n'?
    – amI
    Commented Aug 22, 2016 at 19:47
  • I think it's just a convention in some NLP circles: I believe NLTK uses NN to tag a noun. On the other hand, some NLP classes use NN for 'nominal'. This choice is argued by Halliday and functional grammar, although some may argue that a nominal group is/is too similar to a noun phrase. Finally, in my natural language syntax classes we labelled our trees with just N for any noun. Commented Sep 2, 2016 at 11:36

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