SYMMETRICAL UNITS IN MODULAR GROUP-ALGEBRAS

Let p be a prime, G a locally finite p-group, K a commutative ring of characteristic p. The anti-automorphism g bar arrow pointing right g(- 1) of G extends linearly to an anti-automorphism a bar arrow pointing right a of KG. An element a of KG is called symmetric if a* = a. In t his paper we answer the question: for which G and K do the symmetric u nits of KG form a multiplicative group.