VOLUME 115 NUMBER 1 MAY 1992 WHOLE NUMBER 395 Proceedings JL. OFTHE

AMERICAN MATHEMATICAL SOCIETY

EDITED BY William Adams Jeffry N. Kahn Dale Alspach Barbara Lee Keyfitz, J. Marshall Ash Coordinating Editor for ODE, Maurice Auslander PDE, Global Analysis, and Albert Baernstein Dynamical Systems Eric Bedford Irwin Kra, Managing Editor Andreas R. Blass Peter Li, Coordinating Editor Andrew M. Bruckner for Lie Groups, Topology, Christopher Croke and Geometry Clifford J. Earle, Jr., Wei Y. Loh Coordinating Editor for Joseph S. B. Mitchell Analysis and Operator Theory M. Susan Montgomery, Eric Friedlander Coordinating Editor for Theodore W. Gamelin Algebra, Number Theory, James Glimm, Coordinating and Combinatorics Editor for Applied Charles Pugh Mathematics, Probability, David Sharp and Statistics Hal L. Smith Roe Goodman Ronald M. Solomon Thomas Goodwillie Ronald Stern Lawrence Gray Franklin D. Tall Dennis A. Hejhal John Trangenstein Palle E. T. Jorgensen James West

PROVIDENCE,RHODE ISLAND USA ISSN0002-9939 Proceedings of the American Mathematical Society This journal is devoted entirely to research in pure and applied mathematics.

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Authors are requested to send papers directly to the appropriate Editor (the one whose area of responsibility and expertise, as described below, most closely approximates the subject field of the manuscript). Only when in doubt about an appropriate Editor, should manuscripts be sent to the Coordinating Editor responsible for the area in mathematics most closely connected to the paper. If in doubt about the area, send manuscript to the Managing Editor, to whom all other communication "Department about the journal should also be addressed. (All addresses should include the line of Mathematics", unless another department is indicated.) Managing Editor: Irwin Kra, SUNY at Stony Brook, Stony Brook, NY 11794-3651

1. ODE, PDE, GLOBAL ANALYSIS,AND DYNAMICAL SYSTEMS Coordinating Editor: Barbara Lee Keyfitz, University of Houston, Houston, TX 77204-3476 Partial differential equations Ordinary differential equations and Barbara Lee Keyfitz special functions Hal L. Smith Dynamical systems and global analysis Arizona State University Charles Pugh Tempe, AZ 85287 University of California at Berkeley Berkeley,CA 94720

2. LIE GROUPS, TOPOLOGY, AND GEOMETRY Coordinating Editor : Peter Li, University of California, Irvine, CA 92717 Topological groups and Lie groups (symmetric Metric and geometric topology spaces) James West Roe Goodman Cornell University Rutgers University White Hall New Brunswick, NJ 08903 Ithaca, NY 14853-7901

Riemannian geometry (including affine pseudo- Set-theoretic and general Riemannian, contact, classical, and Lorentzian topology geometries) Franklin D. Tall Christopher Croke University of Toronto University of Pennsylvania Toronto, Ontario, Canada M5S 1A1 Philadelphia, PA 19104 Low dimensional topology and differential Geometric analysis (geometric PDE, minimal topology (knot theory, 3- and 4-man¡folds. surfaces, harmonic maps) and Kahler Gauge-theory) geometry Ronald Stern Peter Li University of California Irvine, CA 92717 Algebraic topology (higher dimensional topology) Thomas Goodwillie Brown University Box 1917 Providence, RI 02912

3. ANALYSISAND OPERATOR THEORY Coordinating Editor: Clifford J. Earle, Jr., Cornell University, White Hall, Ithaca, NY 14853 One complex variable potential theory Functional analysis and operator theory Albert Baernstein Palle E. T. Jorgensen Washington University University of Iowa St. Louis, MO 63130 Iowa City, IA 52242

Several complex variables Functional analysis Eric Bedford Dale Alspach Indiana University Oklahoma State University Swain Hall East Stillwater, OK 74078 Bloomington, IN 47401 Complex variables, functional analysis, and Harmonic and general analysis operator theory J. Marshall Ash Theodore W. Gamelin DePaul University UCLA Chicago, IL 60614 Los Angeles, CA 90024 Analytic number theory and automorphic forms Real analysis Dennis A. Hejhal Andrew Bruckner School of Mathematics University of California University of Minnesota Santa Barbara, CA 93106 Minneapolis, MN 55455

4. ALGEBRA, NUMBER THEORY, AND COMBINATORICS Coordinating Editor: M. Susan Montgomery, University of Southern California, DRB 155, Los Angeles, CA 90089-1113

General number theory Combinatorics William Adams Jeffry N. Kahn University of Maryland Rutgers University College Park, MD 20742 New Brunswick, NJ 08903

General algebra Number theory and automorphic forms Maurice Ausländer Dennis A. Hejhal Brandeis University School of Mathematics P. O. Box 9110 University of Minnesota Waltham, MA 02254-9110 Minneapolis, MN 55455

Group theory Logic and foundations Ronald M. Solomon Andreas R. Blass Ohio State University University of Michigan Columbus, OH 43210 Ann Arbor, MI 48109-1003

Commutative algebra, AT-theory, algebraic groups Eric Friedlander Northwestern University Evanston, IL 60208

5. APPLIED MATHEMATICS, PROBABILITY, AND STATISTICS Coordinating Editor : James Glimm, Department of Applied Mathematics and Statistics, SUNY at Stony Brook, Stony Brook, NY 11794-3600 Probability Applied mathematics Lawrence Gray David Sharp School of Mathematics Theoretic Division University of Minnesota Los Alamos National Laboratory MSB285 Minneapolis, MN 55455 Los Alamos, NM 87545 or Statistics John Trangenstein Wei Y. Loh Duke University Department of Statistics Durham, NC 27706 University of Wisconsin 1210 W. Dayton Street Operations research Madison, WI 53706 Joseph S. B. Mitchell Department of Applied Mathematics and Statistics SUNY at Stony Brook Stony Brook, NY 11794-3600 CONTENTS—Continued from back cover

Approximation of convex bodies by triangles. By Marek Lassak. 207 Ball covering on manifolds with nonnegative Ricci curvature near infinity. By Zhong- dong Liu. 211 Dirichlet polyhedra for cyclic groups in complex hyperbolic space. By Mark B. Phillips 221 A geometric interpretation of Segal's inequality \\ex+Y\\ < \\exl2eYexl2\\. By G. Corach, H. Porta, and L. Recht. 229

G. TOPOLOGY

Intrinsic chirality of complete graphs. By Erica Flapan and Nikolai Weaver. 233 Some remarks on the structure of Mackey functors. By J. P. C. Greenlees and J. P. May 237 Essential laminations in surgered 3-manifolds. By Ying-Qing Wu. 245 k -topologies for right topological semigroups. By John Baker, Neil Hindman, and John Pym. 251 Characterization of separable metric R-trees. By J. C. Mayer, L. K. Mohler, L. G. Oversteegen, and E. D. Tymchatyn. 257 Relations between chain recurrent points and turning points on the interval. By Shihai Li 265 Shadowing property of continuous maps. By Tomás Gedeon and Milan Kuchta .... 271 An extension of Rourke's proof that fi3 = 0 to nonorientable manifolds. By Fredric D. Ancel and Craig R. Guilbault. 283 PROCEEDINGS OF THE AMERICAN MATHEMATICAL SOCIETY CONTENTS Vol. 115, No. 1 May 1992 Whole No. 395

A. ALGEBRA AND NUMBER THEORY

Dehomogenization of gradings to Zariskian filtrations and applications to invertible ideals. By Hui-Shi Li and Freddy Van Oystaeyen . 1 Small congruences and concreteness. By Magdalena Velebilová. 13 Presentations for 3-dimensional special linear groups over integer rings. By Marston Conder, Edmund Robertson, and Peter Williams. 19 Random walk in a Weyl chamber. By Ira M. Gessel and Doron Zeilberger. 27 The distribution of smooth numbers in arithmetic progressions. By Antal Balog and Carl Pomerance. 33 A two-generator presentation for the Picard group. By A. M. Brunner. 45 A test theorem on coherent GCD domains. By Zhao Yicai. 47 Koszul homology of Cohen-Macaulay rings with linear resolutions. By Carlos Rentería and Rafael H. Villarreal. 51

B. ANALYSIS

Quadrature formulas for monotone functions. By Erich Novak. 59 Complete conformai metrics with zero scalar curvature. By Xiaoyun Ma and Robert C. McOwen . 69 Continuous independence and the Ilieff-Sendov conjecture. By Michael J. Miller .... 79 All the infinite nest algebras are isomorphic. By Alvaro Arias. 85 On the existence of invariant measures that behave like area. By Stewart Baldwin ... 89 Hubert spaces of analytic functions between the Hardy and the Dirichlet space. By Alexandru Alemán. 97 Asymptotic behavior of a linear delay difference equation. By R. D. Driver, G. Ladas, and P. N. Vlahos. 105 Smooth approximations in Banach spaces. By J. Vanderwerff. 113 The existence of left averaging functions that are not right averaging. By Tianxuan Miao 121 Inverses generalises d'operateurs non bornes. By J-Ph. Labrousse. 125 Bound on the extreme zeros of orthogonal polynomials. By Mourand E. H. Ismail and Xin Li. 131 Regular matrices and P-sets in ßN\N. II. By Robert E. Atalla. 141 Compositions of continuous functions and connected functions. By Kenneth R. Kellum and Harvey Rosen. 145 Sums of lattice homomorphisms. By S. J. Bernau, C. B. Huijsmans, and B. De Pagter 151 On absolute weighted mean summability methods. By M. Ali Sarigöl. 157 A sharp estimate in an operator inequality. By R. McEachin. 161 '-Representations of the trace-class of an H*-algebra. By Lajos Molnár. 167 Matrix summability of unbounded sequences. By J. DeFranza and K. Zeller. 171 On Opial's inequality for f^K By A. M. Fink. 177 Subharmonic solutions of conservative systems with nonconvex potentials. By A. Fonda and A. C. Lazer. 183

C. APPLIED MATHEMATICS

Finitely additive Gleason measures. By Anatolij DvureCenskij. 191

D. GEOMETRY

The flat strip theorem fails for surfaces with no conjugate points. By Keith Burns .... 199

Continued on inside back cover