Question:
Who was the chair of PSL University in May, 2017?

Context:
 Thierry Coulhon is the chair of PSL University from Feb, 2015 to May, 2017. 
 Marc Mézard is the chair of PSL University from May, 2017 to Oct, 2017. 
 Monique Canto-Sperber is the chair of PSL University from Feb, 2012 to Sep, 2014. 
 Alain Fuchs is the chair of PSL University from Oct, 2017 to Dec, 2022.

Answer:
Question:
Who was the chair of PSL University in May, 2017?

Context:
 Thierry Coulhon is the chair of PSL University from Feb, 2015 to May, 2017. 
 Marc Mézard is the chair of PSL University from May, 2017 to Oct, 2017. 
 Monique Canto-Sperber is the chair of PSL University from Feb, 2012 to Sep, 2014. 
 Alain Fuchs is the chair of PSL University from Oct, 2017 to Dec, 2022.

Answer:
user
Marc Mézard
assistant
Question:
Who was the chair of PSL University in May, 2017?

Context:
 Thierry Coulhon is the chair of PSL University from Feb, 2015 to May, 2017. 
 Marc Mézard is the chair of PSL University from May, 2017 to Oct, 2017. 
 Monique Canto-Sperber is the chair of PSL University from Feb, 2012 to Sep, 2014. 
 Alain Fuchs is the chair of PSL University from Oct, 2017 to Dec, 2022.

Answer:
user
Alain Fuchs
Monique Canto-Sperber
Thierry Coulhon
Alain Fuchs
Monique Canto-Sperber
assistant
Question:
Who was the chair of PSL University in May, 2017?

Context:
 Thierry Coulhon is the chair of PSL University from Feb, 2015 to May, 2017. 
 Marc Mézard is the chair of PSL University from May, 2017 to Oct, 2017. 
 Monique Canto-Sperber is the chair of PSL University from Feb, 2012 to Sep, 2014. 
 Alain Fuchs is the chair of PSL University from Oct, 2017 to Dec, 2022.

Answer:
user
Marc Mézard
assistant