*Editors*: D.G. Bourgin (Houston), B. Jóhnson (Nashville), A. Lelek (Houston), J.S. Mac Nerney (Houston), J.W. Neuberger (Emory), B.H. Neumann (Australian National University), J. Schmidt (Houston)
*Managing Editor*: G.G. Johnson (Houston)
*Associate Managing Editors*: J. Hausen (Houston), J.A. Johnson (Houston)

Houston Journal of Mathematics

*Contents*

**Shair Ahmad, Alan C. Lazer
**

On the Role of Hopf's Maximum Principal in Elliptic Sturmian Theory, pp. 155-158.

**Maurizio Badii, Antonio Croce
**

Regularity in Abstract Differential Equations, pp.
159-167.

**Zvonko Cerin
**

The Shape Category of a Shape Map, pp. 169-182.

**Brian A. Davey
**

On the Lattice of Subvarieties, pp. 183-192.

**Jo Ford, R. W. Heath
**

Incompressible Spaces, pp. 193-198.

**Anthony M. Gaglione
**

A Commutator Identity Proved by Means of the Magnus Algebra, pp.
199-207.

**R. B. King
**

Conjugates of Regular Complete Multipartite Graphs and Hyperpolygonal Graphs, pp.
209-217.

**Rebecca H. Lee
**

Covers and Associated Primes in Noetherian Lattice Modules, pp.
219-239.

**Charles F. Mills, Jan van Mill
**

A Nonsupercompact Continuous Image of a Supercompact Space, pp.
241-247.

**Mary Ellen Rudin
**

The Undecidability of the Existence of a Perfectly Normal Nonmetrizable Manifold, pp. 249-252.

**Walter Rudin
**

Unitarily Invariant Algebras of Continuous Functions on Spheres, pp.
253-265.

**Walter S. Sizer
**

Group Retractions Induced by a Total Order, pp. 267-268.

**George W. Soules
**

An Inequality in the Grassman Algebra, pp.
269-275.

**A. Verma, C. M. Joshi
**

Some Remarks on Summation of Basic Hypergeometric Series, pp. 277-294.

**Bill Watson, Lieven Vanhecke
**

The Structure Equation of an Almost Semi-Kahler Submersion, pp. 295-305.