The Illinois Journal of Mathematics was founded in 1957 by R. Baer, J.L. Doob, A. Taub, G. Whitehead, and O. Zariski. The inaugural volume featured papers of many of the world's leading figures in the key areas of mathematics at the time. Since its inception, the IJM has published many influential papers, most notably the proof of the Four Color Conjecture by K. Appel and W. Haken. Distinguished researchers such as J. Bourgain, A. Calderon, S.S. Chern, H. Kesten, and K. Uhlenbeck have served as Editors of the IJM.

The last 5 years' volumes of the electronic version of the IJM is restricted to subscribers. For further information, please see the IJM Access Notice or contact the IJM office at ijm@math.uiuc.edu.

### Volume 9, Issue 1

#### Publication Date: March 1965

Frontmatter

$T$-groups and their geometry

Arno Cronheim; 1-30

A generator for a set of functions

J. W. Neuberger; 31-39

On the unique factorization theorem in the ring of number theoretic functions

Chin-Pi Lu; 40-46

On finite groups which contain a frobenius factor group

Henry S. Leonard; 47-58

The space of homeomorphisms on a torus

Mary-Elizabeth Hamstrom; 59-65

The type set of a torsion-free group of finite rank

John E. Koehler; 66-86

Dirichlet spaces associated with integro-differential operators. part I

Joanne Elliott; 87-98

The maximal finite groups of $4 \times 4$ integral matrices

On the transformation of sequences and related convergence criteria for continued fractions

David F. Dawson; 123-128

Arithmetic problems concerning cauchy's functional equation II

Ch. Pisot and I. J. Schoenberg; 129-136

Automorphisms of $p$-group

J. E. Adney and Ti Yen; 137-143

Joins of subnormal subgroups

Derek S. Robinson; 144-168

Backmatter