4049
This was shown by Pyotr Novikov in 1955 and a different proof was obtained by William Boone in 1958 .
 person: Pyotr Novikov; person: William Boone
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 person: Pyotr Novikov; person: William Boone