Purple leaf

Powers of the Phantom Ideal

Department of Mathematics, Wilfrid Laurier University


Professor Xianhui Fu, Northeast Normal University, China


Powers of the Phantom Ideal


The mono-epi (ME) exact structure on the morphisms of an exact category (A; E) is introduced and used to prove ideal versions of Salce’s Lemma, Christensen’s (Ghost) Lemma, and Wakamatsu’s Lemma for an exact category.

As an application, it is proved that if G is a finite group and Φ is the ideal of phantom morphisms in the category k[G]-Mod, then Φ^{n−1} is the object ideal generated by projective modules, where n is the nilpotency index of the Jacobson radical J.


Wednesday, Jan. 10, 2018


4 p.m. - 4:50 p.m.


LH3058 (Lazaridis Hall, Room 3058)