89660
If " S " is indexed by a set " I " consisting of all the natural numbers " N " or a finite subset of them , then it is easy to set up a simple one to one coding ( or Gödel numbering ) from the free group on " S " to the natural numbers , such that we can find algorithms that , given " f " ( " w " ) , calculate " w " , and vice versa .
 Gödel
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Gödel