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His work on automata theory earned him the ACM Turing Award in 1976 , while his collaborative work with Christopher Strachey in the 1970 s laid the foundations of modern approaches to the semantics of programming languages .
 person: Christopher 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: Christopher Strachey