文摘
We show the finite metacyclic groups G(p,q)G(p,q) admit a class of projective resolutions which are periodic of period 2q and which in addition possess the properties that a) the differentials are 2×22×2diagonal matrices; b) the Swan–Wall finiteness obstruction (cf. and ) vanishes. We obtain thereby a purely algebraic proof of Petrie's Theorem ([14]) that G(p,q)G(p,q) has free period 2q.