Question: Who is the doctoral adviser of Grigori Perelman ?
Paraphrase: Who is the doctoral counsel of Grigori Perelman ?
SPARQL (Wikidata):  select distinct ?obj where { wd:Q117346 wdt:P184 ?obj . ?obj wdt:P31 wd:Q5 } 
Answer: Yuri Burago, Aleksandr Aleksandrov