cave in vs disagree

cave in

verb
  • To relent; to grant approval against one's initial will. 

  • To collapse inward or downward. 

noun
  • The act of relenting. 

  • The location where something has caved in. 

  • The act of something collapsing or caving in. 

disagree

verb
  • To fail to agree; to have a different opinion or belief. 

  • To fail to conform or correspond with. 

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