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I have several phrases in my text such as

'The changes are consistent with post radiotherapy phrases'

I would like to pick these sentences up

Is there a way of using parts of speech to determine temporal prepositions specifically eg a tag pattern?

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  • At least one example you give ('previous EMR') isn't a preposition. Mar 23 '19 at 16:27
  • OK. Sorry. I've corrected it Mar 23 '19 at 16:44
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    In your example, "post" is not a preposition but a prefix, though it does of course have a temporal meaning. Thus the word should be hyphenated "post-radiotherapy".
    – BillJ
    Mar 28 '19 at 9:16
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Short Answer: Part of speech tags can not be used to determine temporal prepositions.

Long Answer: If you really want to do this, extract the prepositional phrases, and run those phrases through 'prepositional sense disambiguation' system. They will use a combination of the preposition plus the object of the preposition to determine if the PP was indeed being used to indicate a temporal notion.

UPDATE: Also see the book, "Neural Networks for Natural Language Processing" by Yoav Goldberg. Chapter 7.6 walks the reader through the detailed steps of preposition sense disambiguation.

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    But .... "post" is not a preposition but a prefix, so "post-radiotherapy" is a single word, not a prep+noun syntactic construction.
    – BillJ
    Mar 28 '19 at 9:22
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    Lexicographers don't agree on this one. See 4th PoS, en.oxforddictionaries.com/definition/post IMHO, it sure works like a preposition, "The food will be ready post 5pm." (after). One might argue that 'post' is a prefix to '5pm', but it seems cleaner as a preposition. Mar 28 '19 at 22:46
  • It may work like one, but the fact is that it isn't one. It only has noun and verb forms. I would hyphenate post-5pm, just like its opposite "pre-5pm", where "pre" is clearly a prefix, not a prep. By contrast "after" occurs as a temporal preposition in compounds such as "afternoon" "after-care", "after-thought" and the like. Btw, I think the Oxford is wrong -- in the example it gives, "post" is used incorrectly.
    – BillJ
    Mar 29 '19 at 8:31
  • Oxford also recognizes 'pre' as a preposition. Of the 11,000 "event words" that semantically could use the 'post' prefix, dictionaries recognize only 100 - 700 as lexical items. Interesting to note, the dictionaries that don't recognize 'post' as a preposition, also don't recognize the hyphenated entry, leaving us with 10,000+ neologisms. Mar 29 '19 at 14:11
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    I agree - liberties can be taken with hyphens (pre-1701, pre-1702, pre-1703, ...) If 'pre' and 'post' can be attached to any number, and those constructions represent a compound word, than there would be an infinite number of compound words. By treating the prefix as a preposition, you avoid the 'infinite compound word' dilemma. Great quote: "Hyphenation in English is subject to fashion and arbitrary prescription, some of which may appear to give differences between national varieties." Mar 29 '19 at 15:53

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