cohere vs unlink

cohere

verb
  • To stick together physically, by adhesion. 

  • To be consistent as part of a group, or by common purpose. 

unlink

noun
  • A link that is equivalent (under ambient isotopy) to finitely many disjoint circles in the plane. 

verb
  • To decouple; to remove a link from, or separate the links of. 

  • To delete (a file). 

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