Bass orders in non semisimple algebras
Hiroaki Hijikata, Kenji Nishida · Kyoto journal of mathematics · 1994
2.7)A cA 'cA "c... (resp .P c P 'c P " c . . . ) .since ./VP=/ 3 , we have 0-, - 0->P=>P1-H0 (A-exact), 0-0 n P-, P->g(P)->0 (A-exact).Since /(P1)< l(P), 7r(P) is projective by the induction assumption