23744
Rather , redshifting due to the expansion of space is known as cosmological redshift , which can be derived purely from the Robertson-Walker metric under the formalism of General Relativity .
 person: Robertson-Walker
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities: Robertson-Walker 
Answer:
 person: Robertson-Walker