In Kazuo Okamoto and Yousuke Ohyama's paper "Mathematical works of Hiroshi Umemura", Annales de la faculté des sciences de Toulouse Mathématiques, XXIX, no. 5 (2020) pp. 1053-1062, there is a reference to a meeting at the IHES in 2010 between Umemura, Pommaret, and Malgrange. This is described as follows:
Umemura, Pommaret and Malgrange met at IHES in the fall 2010. Three researchers have their own differential Galois theory. After a stormy discussion, Umemura and Pommaret did not achieve consensus on differential Galois theory. This is the last time that Umemura met Pommaret.
What were the issues / differences in approach that led to this "stormy discussion"?
