on a string vs tractable

on a string

prep
  • Under one's control or influence. 

tractable

adj
  • Easy to deal with or manage 

  • Capable of being easily led, taught, or managed. 

  • Capable of being shaped; malleable. 

  • Sufficiently operationalizable or useful to allow a mathematical calculation to proceed toward a solution. 

  • Algorithmically solvable fast enough to be practically relevant, typically in polynomial time. 

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