S. T. Aheam, M. L. Huber, and G. J . Sherman

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COMMUNICATIONS IN ALGEBRA

Volume 27, Number 3, 1999

Z. Pogorzaty

Classical Quotient Rings of Incidence A l g e b r a s . . . 999 E. Spiegel

Finite Groups Can Be Arbitrarily H a m i l t o n i a n . . . 1013

S. T. Aheam, M. L. Huber, and G. J . Sherman

On Local-Extensions of A l g e b r a s . . . 1017

Ma. I. R. Martins and J . A. de la Pena

Almost Irreducible Tensor Squares . . . 1033

G. Malle

A Character Theoretic Condition Characterizing Nilpotent

Groups . . . 1053 S. M. Gagola, Jr., and M. L. Lewis

Howson Property and One-ReIator G r o u p s . . . 1057 /. Kapovich

Golod Pair and Golod I n v a r i a n t . . . 1073

K.Lee

On n-Presented Modules and Almost Excellent Extensions... 1091 W.Xue

Cohen-Macaulay Approximations from the Viewpoint of

Triangulated C a t e g o r i e s . . . 1103 K. Kato

Surfaces of Low Degree Containing a General Canonical

Curve . . . 1127

C. Ciliberto and J . Harris

vn

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Vlll CONTENTS Blowing Up Determinantal Space Curves and Varieties of

Codim 2 . . . 1141

A. Gimigliano and A. Lorenzini

The Semisimplicity of Smash Products of Quantum

Commutative A l g e b r a s . . . 1165

S. Yang and Z. Wang

Irreducible Characters of a Sylow /^-Subgroup of the

Orthogonal Group . . . 1171

M. Marjoram

Lines on del Pezzo Surfaces with K} = 1 in Characteristic ^ 2 ... 1197

P. Cragnolini and P. A. Oliverio

Covering the Group PSL,,(F) by the Square of a Conjugacy

C l a s s . . . 1207 A. Lev

A Quantitative Version of a Lemma of Shafarevich-Ishkhanov... 1255

R. Meshulam and J . Sonn

On the Order of the Antipode of Hopf Algebras in ^YD ... 1261 Y. Kashina

Priifer --Multiplication Domains and Torsion Theories . . . 1275

J . M. Garcia, P. Jara, and E. Santos

Some Topics on HOM ^(M,-) in the Category of Relative

Hopf M o d u l e s . . . 1297 B. Ion

A Lower Bound for the Number of Intermediary Rings . . . 1307

A. Jaballah

On the Nucleus of Certain Lie Admissible R i n g s . . . 1313

E. Kleinfeld and M. Kleinfeld

On Yetter-Drinfeld Categories and H - C o m m u t a t i v i t y . . . 1321

M. Cohen, D. Fischman, and S. Montgomery

Coalgebra Extensions and Algebra Coextensions of Galois Type . . . . 1347

T. Brzeziiiski and P. M. Hajac

Dependence Integrate dans les Anneaux de Series F o r m e l l e s . . . 1369

A. Benhissi

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ISWTENTS ix

|b0n Injective Modules Whose Endomorphism Rings Are

Smple Artinian . . . 1385 y. Hirano, C. Y. Hong, J. Y. Kirn, andJ. K. Park

On the Defining Equations of Multi-graded R i n g s . . . 1393

J. Ribbe

On the Cyclic Homology of Commutative Algebras over

Arbitrary Ground R i n g s . . . 1403 G. Cortinas

The Quantum Double of a CoFrobenius Hopf A l g e b r a . . . 1413 Y. Zhang

Some Quantum V^s with One Point . . . 1429 B. Shelton and M. Vancliff

Relative Critical Composition Series . . . 1445 H. Lee and P. Vachuska

Extension Closure of A:-Torsionfree Modules . . . 1457

Z. Huang

On Divided Commutative R i n g s . . . 1465

A. Badawi

Exterior Power Operations in the Representation Theory of

the Classical Weyl Groups . . . 1475 7. M. Bryden

Erratum . . . 1499

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COMMUNICATIONS IN ALGEBRA

Volume 27, Number 4,1999

0. A. S. Karamzadeh and A. A. Koochakpoor

The Rees Valuations of a Module over a Two-Dimensional

Regular Local R i n g . . . 1515

R. Mohan

Cocycles on a Finite Dimensional Quotient of Ug(sl(l)) ... 1533

/. Boca

Free Subgroups of SOs{Q) . . . 1555

G. Liu and L. C. Robertson

Finite Partition Lattices and Butler G r o u p s . . . 1571 C. De Vivo and C. Metelli

Sur un Exemple de Wadsworth . . . 1591

A, Ay ache

Summands of Dual Groups . . . 1599 G. Schlitt

Exact Envelopes of Complexes . . . 1615

E. E. Enochs and J . R. Garcia Rozas

Simply Presented Tag Modules . . . 1629

F. Richman

Maximal Commutative Subalgebras of Matrix A l g e b r a s . . . 1649 Y. K. Song

On VOA Associated with Special Jordan Algebras . . . 1665

C. H. Lam

Principally Quasi-injective M o d u l e s . . . 1683 W. K. Nicholson, J. K. Park, and M. F. Yousif

Automorphisms of Infinite-Dimensional Square-Free Algebras... 1695

F. W. Anderson and B. K. D 'Ambrosia

vii

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viii CONTENTS

Artinian Algebras and Differential F o r m s . . . 1711 1

G. Cortinas and F. Krongold \

Factorial Domains Not Satisfying the Krull Intersection , P r o p e r t y . . . 1717 l

P. Zanardo \

Elasticity and Ramification . . . 1729 ,

N. Gonzalez

^\

Preserving of Covers by Hopf I n v a r i a n t s . . . 1737 \

J . R. Garcia Rows and B. Torrecillas [

Morita Equivalence for Infinite Matrix Rings . . . 1751 |

Y.XuandK.-P. Shum f

Integral Closure of a Marot Ring Whose Regular Ideals Are i Finitely Generated . . . 1783 1 - G. W. Chang \ Decomposition of Comodules . . . 1797 ,

J . M. Garcia, P. Jara, and L. M. Merino

Quotient Finite Dimensional Modules with ACC on Subdirectly

Irreducible Submodules Are Noetherian . . . 1807

C. Faith

Asymptotic Primes and Sequences over a M o d u l e . . . 1811

C. Naude

Isotropy of 8-Dimensional Quadratic Forms over Function

Fields of Q u a d r i c s . . . 1823

0. T. Izhboldin and N. A. Karpenko

Actions of GZ,,(2,Q on C(l,3) and Its Four Dimensional

Representations . . . 1843

V. K. Kharchenko, Jaime Keller, and S. Rodriguez-Romo

A Characterization of PSp(4,K) ... 1879

C. Altseimer

Remarks on the Twisted Adjoint Representation of R,[G]... 1889 E. S. Letzter

Inductive Limits of Multispectra . . . 1895

A. Verschoren and N. A. Soultan

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CONTENTS ix Dyslexia and Duals of Hopf Algebras in Braided Monoidal

C a t e g o r i e s . . . 1903 J . N. Alonso Alvarez and R. Gonzalez Rodriguez

Derivations with Algebraic Values of Bounded Degree . . . 1911 T.-K. Lee and T.-C. Lee

On Semilocal Modules and R i n g s . . . 1921 C. Lomp

On Residually Finite Groups in Which Commutators Are Engel .... 1937 P. Shumyatsky

Filtrations on a Ring and Asymptotic D e v i a t i o n s . . . 1941 P. Ayegnon

On the Z-Module Structure of a Free Semialternative Ring . . . 1951 M. Bremner

Unique Factorization Rings with Zero Divisors . . . 1967 A. G. Agargiin, D. D. Anderson, and S. Valdes-Leon

Semigroups with Magnifiers Admitting Minimal Subsemigroups .... 1975 M. Gutan