tracing vs undirected graph

tracing

noun
  • A record in the form of a graph made by a device such as a seismograph. 

  • The process of finding something that is lost by studying evidence. 

  • A regular path or track; a course. 

  • The reproduction of an image made by copying it through translucent paper. 

undirected graph

noun
  • A graph in which the edges are not ordered, so the edge (a, b) is identical to the edge (b, a). 

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