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In the early 1980 s , a combination of results due to Simon Donaldson and Michael Freedman led to the discovery of exotic " R " s : there are uncountably many pairwise non-diffeomorphic open subsets of " R " each of which is homeomorphic to " R " , and also there are uncountably many pairwise non-diffeomorphic differentiable manifolds homeomorphic to " R " that do not embed smoothly in " R " .
 person: Simon Donaldson; person: Michael Freedman
Given options, please tell me the categories of all the listed entity words.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} 
 Entities: Simon Donaldson, Michael Freedman 
Answer:
 person: Simon Donaldson; person: Michael Freedman