It could be a time factor. That was published in 2006. "An introduction to optimization and to the calculus of variations" is published in 2017 https://www.ljll

It could be a time factor. That was published in 2006. "An introduction to optimization and to the calculus of variations" is published in 2017 https://www.ljll.math.upmc.fr/mazari/documents/Cours_Pristina_Mazari.pdf https://www.ljll.math.upmc.fr/mazari/documents/Cours_Pristin...