10486
Appending this schema , as well as the axiom of regularity ( first proposed by John von Neumann ) , to Zermelo set theory yields the theory denoted by " ZF " .
 person: John von Neumann; person: Zermelo
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 person: John von Neumann; person: Zermelo