6774
In his spare time Strachey developed a program for the game of draughts ( also known as " checkers " ) , which he finished a preliminary version in May 1951 .
 person: Strachey
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: Strachey