decidable vs purposive

decidable

adj
  • capable of being decided. 

  • in intuitionistic logic, a proposition P is decidable in a given theory if it can be proven from the theory that "either P or not P", i.e. in symbols: P∨¬P. 

  • describing a set for which there exists an algorithm that will determine whether any element is or is not within the set in a finite amount of time. 

purposive

adj
  • Possessed of a firm purpose. 

  • Serving a particular purpose; adapted to a given purpose, especially through natural evolution. 

  • Done or performed with a conscious purpose or intent. 

  • Pertaining to or demonstrating purpose. 

  • Pertaining to purpose, as reflected in behaviour or mental activity. 

  • Of a clause or conjunction: expressing purpose. 

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