Published by Duke University Press since its inception in 1935, the Duke Mathematical Journal is one of the world's leading mathematical journals. Without specializing in a small number of subject areas, it emphasizes the most active and influential areas of current mathematics.

### Volume 73, Number 2

#### Publication Date: February 1994

On Poisson pairs associated to modified $R$-matrices

Dmitrii Gurevich and Dmitrii Panyushev; 249-255

Third derivative estimates for Dirichlet's problem in convex domains

Stephen J. Fromm and David Jerison; 257-268

Hypergeometric functions and rings generated by monomials

The geometry of properly embedded special surfaces in $\mathbf{R}^3$; e.g., surfaces satisfying $aH+bK=1$, where $a$ and $b$ are positive

Harold Rosenberg and Ricardo Sa Earp; 291-306

Numerical invariants of perverse sheaves

David B. Massey; 307-369

Kleinian groups with small limit sets

Richard D. Canary and Edward Taylor; 371-381

Crystal bases of modified quantized enveloping algebra

Masaki Kashiwara; 383-413

Lie bialgebroids and Poisson groupoids

Kirill C. H. Mackenzie and Ping Xu; 415-452

Holonomic $q$-difference system of the first order associated with a Jackson integral of Selberg type

Katsuhisa Mimachi; 453-468

On minuscule representations, plane partitions and involutions in complex Lie groups

John R. Stembridge; 469-490