feedforward vs preface

feedforward

verb
  • To respond in advance 

noun
  • An anticipatory response to expected changes in the environment of a system 

preface

verb
  • To introduce or make a comment before (the main point). 

  • To give a preface to. 

noun
  • An introduction, or series of preliminary remarks. 

  • A title or epithet. 

  • The beginning or introductory portion that comes before the main text of a document or book. 

  • The prelude or introduction to the canon of the Mass. 

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