153225
Many objects of central interest in algebraic topology can be seen as functors , which are difficult to analyze directly , so the idea is to replace them with simpler functors which are sufficiently good approximations for certain purposes .
 None
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:  
Answer:
 None