behoove vs constrain

behoove

verb
  • To befit, be appropriate or necessary to somebody. Alternative form of behove. 

  • To be fitting. 

constrain

verb
  • To force physically, by strong persuasion or pressuring; to compel; to oblige. 

  • To keep within close bounds; to confine. 

  • To reduce a result in response to limited resources. 

How often have the words behoove and constrain occurred in a corpus of books? (source: Google Ngram Viewer )