No CrossRef data available.
Published online by Cambridge University Press: 24 October 2008
Let
be a series of type Ω of the group G. By this we mean that Ω is an ordered set (we shall always understand ‘ordered’ to mean ‘totally ordered’) and Λσ and Vσ are subgroups of G satisfying
(i) Vσ ◃ Λσ for all σεΩ,
(ii) Λσ ≤ Vτ if σ < τ
(iii) , where G−1 denotes the set of elements ≠ 1 of G and Λσ−Vσ the set of elements of Λσ not belonging to Vσ,
(iv) Vσ ≠ Λσ for all σ ε Ω.