ordering vs partially ordered set

ordering

noun
  • Arrangement in a sequence. 

  • The placement of an order for goods or services. 

  • The act or ceremony of ordaining, as priests or deacons. 

partially ordered set

noun
  • The ordered pair comprising a set and its partial order. 

  • A set that has a given, elsewhere specified partial order. 

How often have the words ordering and partially ordered set occurred in a corpus of books? (source: Google Ngram Viewer )