VOLUME 324 RANSACTIONS OF THE AMERICAN MATHEBRMATICAL SOC 2 EDITED BY Avner D. Ash James E. Baumgartner James W. Cannon Sun-Yung A. Chang Ralph Cohen Richard Durrett David Jerison Jerry L. Kazdan Roger D. Nussbaum Carl Pomerance Judith D. Sally David J. Saltman, Managing Editor Masamichi Takesaki Audrey Terras PROVIDENCE, RHODE ISLAND USA ISSN 0002-9947 Copying and reprinting. Individual readers of this publication, and nonprofit libraries acting for them, are permitted to make fair use of the material, such as to copy a chapter for use in teaching or research. Permission is granted to quote brief passages from this publication in reviews, provided the customary acknowledgement of the source is given. Republication, systematic copying, or multiple reproduction of any material in this publication (including abstracts) is permitted only under license from the American Mathematical Society. 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The paper used in this book is acid-free and falls within the guidelines established to ensure permanence and durability. TRANSACTIONS OF THE AMERICAN MATHEMATICAL SOCIETY CONTENTS Vol. 324, No. 1 March 1991 Whole No. 670 Generalized iteration of forcing By M. GrosZEK and T. JECH Zeros of solutions and of Wronskians for the differential equation L,y + p(x)y =0 By UR ELIAs Relative cohomology and projective twistor diagrams By S. A. HUGGETT and M. A. SINGER Box-spaces and random partial orders By BELA BOLLoBAs and GRAHAM BRIGHTWELL Strong Bertini theorems By STEVEN D1Az and DAVID HARBATER Nonsingular algebraic curves in RP! x RP! By SACHIKO MATSUOKA Boundary value problems for degenerate elliptic-parabolic equations of the fourth order By ROBERT G. ROOT On vector bundles on 3-folds with sectional genus | By EDOARDO BALLICO Determinant expression of Selberg zeta functions. I By SHIN-YA KOYAMA On the interior of subsemigroups of Lie groups By KARL H. HOFMANN and WOLFGANG A. F. RUPPERT On the characteristic classes of actions of lattices in higher rank Lie groups By GARRETT STUCK Similarity orbits and the range of the generalized derivation X — MX — XN By ALLEN SCHWEINSBERG Optimal Hélder and L? estimates for 0, on the boundaries of real ellip- soids in C” By MEI-Cu1 SHAW Hausdorff dimension of divergent Teichmiiller geodesics By HowaARD MASUR The decompositions of Schur complexes By Hyounc J. Ko A convergent framework for the multicomponent KP-hierarchy By G. F. HELMINCK and G. F. Post Extending discrete-valued functions By JOHN KULESZA, RONNIE LEvy and PETER NYIKOS Periodicity and decomposability of basin boundaries with irrational maps on prime ends By RUSSELL B. WALKER On the distance of subspaces of /? to E By WILLIAM B. JOHNSON and GIDEON SCHECHTMAN Stable patterns in a viscous diffusion equation By A. NovicK-CoHEN and R. L. PEGo Lines on the Fermat quintic threefold and the infinitesimal generalized Hodge conjecture By ALBERTO ALBANO and SHELDON KATZ Noether-Lefschetz locus for surfaces By SuNG-OckK KIM Markov partitions for expanding maps of the circle By MATTHEW STAFFORD Maximal representations of surface groups in bounded symmetric domains By Luis HERNANDEZ Infinitesimal rigidity for the action of SL(n,Z) on T” By JAMEs W. LEwiIs Symplectic double groupoids over Poisson (ax + b)-groups By KENTARO MIKAMI Vol. 324, No. 2 April 1991 Whole No. 671 Commutation methods applied to the mKdV-equation By F. GEszTEsy, W. SCHWEIGER and B. SIMON Ramsey theorems for knots, links and spatial graphs By SEIYA NEGAMI Ultra-irreducibility of induced representations of semidirect products By HENRIK STETKAR Local singularities such that all deformations are tangentially flat By BERND HERZOG Construction of units in integral group rings of finite nilpotent groups By JURGEN RITTER and SUDARSHAN K. SEHGAL The Selberg trace formula. VIII, Contribution from the continuous spec- trum By M. Scott OsBoRNE and GARTH WARNER A generalized Berele-Schensted algorithm and conjectured Young tableaux for intermediate symplectic groups By ROBERT A. PROCTOR On the growth of solutions of f” + gf’ +hf =0 By SIMON HELLERSTEIN, JOSEPH MILEs and JOHN Ross! Hankel operators on the Bergman space of bounded symmetric domains By KEHE ZHU The Frobenius-Perron operator on spaces of curves By P. Gora and A. BOYARSKY A cohomological approach to the Brauer-Long group and the groups of Galois extensions and strongly graded rings By S. CAENEPEEL and M. BEATTIE Relative Frobenius of plane singularities By D. DAIGLE Prescribing curvature on compact surfaces with conical singularities By Marc TROYANOV Univalence criteria and quasiconformal extensions By J. M. ANDERSON and A. HINKKANEN On pseudo-differentiability By ROBERTO COMINETTI Linearization of bounded holomorphic mappings on Banach spaces By JORGE MUJICA On certain partial differential operators of finite odd type By A. ALEXANDROU HIMONAS The existence of generalized isothermal coordinates for higher dimensional Riemannian manifolds By JIANGUO CAO