## Advanced Studies in Pure Mathematics

- Adv. Stud. Pure Math.
- Groups and Combinatorics: In memory of Michio Suzuki, E. Bannai, H. Suzuki, H. Yamaki and T. Yoshida, eds. (Tokyo: Mathematical Society of Japan, 2001), 279 - 288

### Rationally Determined Group Modules

#### Abstract

Green's correspondence of group modules finds its simplest expression when a finite multiplicative group $G$ has a trivial intersection Sylow $p$-subgroup $P$, for some prime $p$. Then it is between all isomorphism classes of projective-free $\mathbf{R}G$-lattices $\mathbf{L}$ and all isomorphism classes of projective-free $\mathbf{R}N$-lattices $\mathbf{K}$, where $\mathbf{R}$ is a suitable valuation ring and $N$ is the normalizer of $P$ in $G$. In that case we show in Theorem 3.2 below that the $\mathbf{R}G$-lattice $\mathbf{L}$ is determined by its associated lattices over the residue field and field of fractions of $\mathbf{R}$ if and only if $\mathbf{K}$ has this same property. By Theorem 3.7 some important $\mathbf{R}G$-lattices $\mathbf{L}$ have this property of being “rationally determined.” So it would be worthwhile to see if the $\mathbf{R}N$-lattices with this property (and perhaps with other properties preserved by this Green correspondence) could be classified.

#### Article information

**Dates**

Received: 29 May 1999

Revised: 18 May 2000

First available in Project Euclid:
29 December 2018

**Permanent link to this document**

https://projecteuclid.org/
euclid.aspm/1546124703

**Digital Object Identifier**

doi:10.2969/aspm/03210279

**Mathematical Reviews number (MathSciNet)**

MR1893495

**Zentralblatt MATH identifier**

1009.20009

#### Citation

Dade, Everett C. Rationally Determined Group Modules. Groups and Combinatorics: In memory of Michio Suzuki, 279--288, Mathematical Society of Japan, Tokyo, Japan, 2001. doi:10.2969/aspm/03210279. https://projecteuclid.org/euclid.aspm/1546124703