matching vs not positive

matching

noun
  • A set of independent edges in a given graph, i.e. a set of edges which do not intersect, such that pairs of vertices are "matched" to each other one to one. 

  • The process by which things are matched together or paired up. 

adj
  • The same as another; sharing the same design. 

not positive

How often have the words matching and not positive occurred in a corpus of books? (source: Google Ngram Viewer )