Non-negative integer valued functions on commutative groups, I
R. Biggs, Morio Sasaki, Takayuki Tamura · Proceedings of the Japan Academy Series A Mathematical Sciences · 1965
T. Tamura, one of the authors, introduced "an indexed group" which means a commutative group G with a non-negative integer valued function I(x, y) defined on G G and satisfying the ollowing conditions:(A) I(x, y)-I(y, x) (B) I(x, y)/ I(xy, z)-I(x, yz)/ I(y, z) for any x, y, z e G (C) For any x e G, there is a positive integer m (depending on x) such that I(x , x)>O.(D) I(e, e)-