Leonid Libkin

Pablo Barceló, Juan L. Reutter, Leonid Libkin: Parameterized regular expressions and their languages. Theor. Comput. Sci. 474: 21-45 (2013)

Leonid Libkin, Wim Martens, Domagoj Vrgoc: Querying graph databases with XPath. ICDT 2013: 129-140

Claire David, Amélie Gheerbrant, Leonid Libkin, Wim Martens: Containment of pattern-based queries over data trees. ICDT 2013: 201-212

Pablo Barceló, Diego Figueira, Leonid Libkin: Graph Logics with Rational Relations. CoRR abs/1304.4150 (2013)

Rada Chirkova, Leonid Libkin, Juan L. Reutter: Tractable XML data exchange via relations. Frontiers of Computer Science 6(3): 243-263 (2012)

Claire David, Leonid Libkin, Tony Tan: Efficient reasoning about data trees via integer linear programming. ACM Trans. Database Syst. 37(3): 19 (2012)

Pablo Barceló, Leonid Libkin, Anthony Widjaja Lin, Peter T. Wood: Expressive Languages for Path Queries over Graph-Structured Data. ACM Trans. Database Syst. 37(4): 31 (2012)

Pablo Barceló, Leonid Libkin, Miguel Romero: On Low Treewidth Approximations of Conjunctive Queries. AMW 2012: 91-101

Leonid Libkin, Domagoj Vrgoc: Regular path queries on graphs with data. ICDT 2012: 74-85

Amélie Gheerbrant, Leonid Libkin, Tony Tan: On the complexity of query answering over incomplete XML documents. ICDT 2012: 169-181

Pablo Barceló, Diego Figueira, Leonid Libkin: Graph Logics with Rational Relations and the Generalized Intersection Problem. LICS 2012: 115-124

Leonid Libkin, Domagoj Vrgoc: Regular Expressions for Data Words. LPAR 2012: 274-288

Pablo Barceló, Leonid Libkin, Miguel Romero: Efficient approximations of conjunctive queries. PODS 2012: 249-260

Leonid Libkin, Cristina Sirangelo: Data exchange and schema mappings in open and closed worlds. J. Comput. Syst. Sci. 77(3): 542-571 (2011)

Marcelo Arenas, Pablo Barceló, Leonid Libkin: Regular Languages of Nested Words: Fixed Points, Automata, and Synchronization. Theory Comput. Syst. 49(3): 639-670 (2011)

André Hernich, Leonid Libkin, Nicole Schweikardt: Closed world data exchange. ACM Trans. Database Syst. 36(2): 14 (2011)

Nadime Francis, Claire David, Leonid Libkin: A Direct Translation from XPath to Nondeterministic Automata. AMW 2011

Rada Chirkova, Leonid Libkin, Juan L. Reutter: Tractable XML data exchange via relations. CIKM 2011: 1629-1638

Pablo Barceló, Leonid Libkin, Juan L. Reutter: Parameterized Regular Expressions and Their Languages. FSTTCS 2011: 351-362

Claire David, Leonid Libkin, Tony Tan: Efficient reasoning about data trees via integer linear programming. ICDT 2011: 18-29

Leonid Libkin: Incomplete information and certain answers in general data models. PODS 2011: 59-70

Pablo Barceló, Leonid Libkin, Juan L. Reutter: Querying graph patterns. PODS 2011: 199-210

Pablo Barceló, Leonid Libkin, Juan L. Reutter: Parameterized Regular Expressions and their Languages. CoRR abs/1107.0577 (2011)

Marcelo Arenas, Pablo Barceló, Leonid Libkin, Filip Murlak: Relational and XML Data Exchange. Synthesis Lectures on Data Management, Morgan & Claypool Publishers 2010

Leonid Libkin, Cristina Sirangelo: Disjoint pattern matching and implication in strings. Inf. Process. Lett. 110(4): 143-147 (2010)

Pablo Barceló, Leonid Libkin, Antonella Poggi, Cristina Sirangelo: XML with incomplete information. J. ACM 58(1): 4 (2010)

Leonid Libkin, Cristina Sirangelo: Reasoning about XML with temporal logics and automata. J. Applied Logic 8(2): 210-232 (2010)

Solmaz Kolahi, Leonid Libkin: An information-theoretic analysis of worst-case redundancy in database design. ACM Trans. Database Syst. 35(1) (2010)

Pablo Barceló, Leonid Libkin, Juan L. Reutter: On Incomplete XML Documents with Integrity Constraints. AMW 2010

Anthony Widjaja To, Leonid Libkin: Algorithmic Metatheorems for Decidable LTL Model Checking over Infinite Systems. FOSSACS 2010: 221-236

Shun'ichi Amano, Claire David, Leonid Libkin, Filip Murlak: On the tradeoff between mapping and querying power in XML data exchange. ICDT 2010: 155-164

Ting Deng, Wenfei Fan, Leonid Libkin, Yinghui Wu: On the aggregation problem for synthesized web services. ICDT 2010: 242-251

Claire David, Leonid Libkin, Tony Tan: On the Satisfiability of Two-Variable Logic over Data Words. LPAR (Yogyakarta) 2010: 248-262

Pablo Barceló, Carlos A. Hurtado, Leonid Libkin, Peter T. Wood: Expressive languages for path queries over graph-structured data. PODS 2010: 3-14

Claire David, Leonid Libkin, Filip Murlak: Certain answers for XML queries. PODS 2010: 191-202

Leonid Libkin, Victor Vianu: Introduction to PODS 2007 special section. J. ACM 56(6) (2009)

Leonid Libkin, Cristina Sirangelo: Open and Closed World Assumptions in Data Exchange. Description Logics 2009

Shun'ichi Amano, Leonid Libkin, Filip Murlak: XML schema mappings. PODS 2009: 33-42

Leonid Libkin: The finite model theory toolbox of a database theoretician. PODS 2009: 65-76

Pablo Barceló, Leonid Libkin, Antonella Poggi, Cristina Sirangelo: XML with incomplete information: models, properties, and query answering. PODS 2009: 237-246

Leonid Libkin: Expressive Power of Query Languages. Encyclopedia of Database Systems 2009: 1081-1083

Anthony Widjaja To, Leonid Libkin: Algorithmic metatheorems for decidable LTL model checking over infinite systems. CoRR abs/0910.4932 (2009)

Marcelo Arenas, Pablo Barceló, Leonid Libkin: Game-based notions of locality over finite models. Ann. Pure Appl. Logic 152(1-3): 3-30 (2008)

Marcelo Arenas, Leonid Libkin: XML data exchange: Consistency and query answering. J. ACM 55(2) (2008)

Rajeev Alur, Marcelo Arenas, Pablo Barceló, Kousha Etessami, Neil Immerman, Leonid Libkin: First-Order and Temporal Logics for Nested Words. Logical Methods in Computer Science 4(4) (2008)

Marcelo Arenas, Wenfei Fan, Leonid Libkin: On the Complexity of Verifying Consistency of XML Specifications. SIAM J. Comput. 38(3): 841-880 (2008)

Leonid Libkin: Introduction to the PODS 2007 special section. ACM Trans. Database Syst. 33(4) (2008)

Leonid Libkin, Cristina Sirangelo: Reasoning about XML with Temporal Logics and Automata. LPAR 2008: 97-112

Anthony Widjaja To, Leonid Libkin: Recurrent Reachability Analysis in Regular Model Checking. LPAR 2008: 198-213

Leonid Libkin, Cristina Sirangelo: Data exchange and schema mappings in open and closed worlds. PODS 2008: 139-148

Rajeev Alur, Marcelo Arenas, Pablo Barceló, Kousha Etessami, Neil Immerman, Leonid Libkin: First-Order and Temporal Logics for Nested Words. CoRR abs/0811.0537 (2008)

Thomas Eiter, Leonid Libkin: Preface. Theor. Comput. Sci. 371(3): 147 (2007)

Michael Benedikt, Leonid Libkin, Frank Neven: Logical definability and query languages over ranked and unranked trees. ACM Trans. Comput. Log. 8(2) (2007)

Marcelo Arenas, Pablo Barceló, Leonid Libkin: Regular Languages of Nested Words: Fixed Points, Automata, and Synchronization. ICALP 2007: 888-900

Marcelo Arenas, Pablo Barceló, Leonid Libkin: Combining Temporal Logics for Querying XML Documents. ICDT 2007: 359-373

Rajeev Alur, Marcelo Arenas, Pablo Barceló, Kousha Etessami, Neil Immerman, Leonid Libkin: First-Order and Temporal Logics for Nested Words. LICS 2007: 151-160

Solmaz Kolahi, Leonid Libkin: XML design for relational storage. WWW 2007: 1083-1092

Leonid Libkin: Normalization Theory for XML. XSym 2007: 1-13

Leonid Libkin (Ed.): Proceedings of the Twenty-Sixth ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems, June 11-13, 2007, Beijing, China. ACM 2007, isbn 978-1-59593-685-1

Leonid Libkin: Embedded Finite Models. Bulletin of the EATCS 90: 134-149 (2006)

Leonid Libkin: Locality of Queries and Transformations. Electr. Notes Theor. Comput. Sci. 143: 115-127 (2006)

Leonid Libkin: Logics for Unranked Trees: An Overview. Logical Methods in Computer Science 2(3) (2006)

Thomas Eiter, Leonid Libkin: Introduction to special ICDT section. ACM Trans. Database Syst. 31(3): 769 (2006)

Leonid Libkin: Data exchange and incomplete information. PODS 2006: 60-69

Solmaz Kolahi, Leonid Libkin: On redundancy vs dependency preservation in normalization: an information-theoretic study of 3NF. PODS 2006: 114-123

Leonid Libkin: Logics for Unranked Trees: An Overview. CoRR abs/cs/0606062 (2006)

Marcelo Arenas, Leonid Libkin: An information-theoretic approach to normal forms for relational and XML data. J. ACM 52(2): 246-283 (2005)

Marcelo Arenas, Wenfei Fan, Leonid Libkin: Consistency of XML Specifications. Inconsistency Tolerance 2005: 15-41

Leonid Libkin: Logics for Unranked Trees: An Overview. ICALP 2005: 35-50

Pablo Barceló, Leonid Libkin: Temporal Logics over Unranked Trees. LICS 2005: 31-40

Marcelo Arenas, Leonid Libkin: XML data exchange: consistency and query answering. PODS 2005: 13-24

Thomas Eiter, Leonid Libkin (Eds.): Database Theory - ICDT 2005, 10th International Conference, Edinburgh, UK, January 5-7, 2005, Proceedings. Lecture Notes in Computer Science 3363, Springer 2005, isbn 3-540-24288-0

Leonid Libkin: Elements of Finite Model Theory. Springer 2004, isbn 3-540-21202-7

Marcelo Arenas, Leonid Libkin: A normal form for XML documents. ACM Trans. Database Syst. 29: 195-232 (2004)

Marcelo Arenas, Pablo Barceló, Leonid Libkin: Game-Based Notions of Locality Over Finite Models. CSL 2004: 175-189

Denilson Barbosa, Alberto O. Mendelzon, Leonid Libkin, Laurent Mignet, Marcelo Arenas: Efficient Incremental Validation of XML Documents. ICDE 2004: 671-682

Marcelo Arenas, Pablo Barceló, Ronald Fagin, Leonid Libkin: Locally Consistent Transformations and Query Answering in Data Exchange. PODS 2004: 229-240

Guozhu Dong, Leonid Libkin, Limsoon Wong: Incremental recomputation in local languages. Inf. Comput. 181(2): 88-98 (2003)

Leonid Libkin: A collapse result for constraint queries over structures of small degree. Inf. Process. Lett. 86(5): 277-281 (2003)

Michael Benedikt, Leonid Libkin, Thomas Schwentick, Luc Segoufin: Definable relations and first-order query languages over strings. J. ACM 50(5): 694-751 (2003)

Michael Benedikt, Martin Grohe, Leonid Libkin, Luc Segoufin: Reachability and connectivity queries in constraint databases. J. Comput. Syst. Sci. 66(1): 169-206 (2003)

Leonid Libkin: Expressive power of SQL. Theor. Comput. Sci. 296(3): 379-404 (2003)

Leonid Libkin: Variable independence for first-order definable constraints. ACM Trans. Comput. Log. 4(4): 431-451 (2003)

Leonid Libkin, Frank Neven: Logical Definability and Query Languages over Unranked Trees. LICS 2003: 178-187

Marcelo Arenas, Leonid Libkin: An information-theoretic approach to normal forms for relational and XML data. PODS 2003: 15-26

Wenfei Fan, Leonid Libkin: On XML integrity constraints in the presence of DTDs. J. ACM 49(3): 368-406 (2002)

Michael Benedikt, Leonid Libkin: Aggregate Operators in Constraint Query Languages. J. Comput. Syst. Sci. 64(3): 628-654 (2002)

Leonid Libkin, Limsoon Wong: Lower bounds for invariant queries in logics with counting. Theor. Comput. Sci. 288(1): 153-180 (2002)

Martín Abadi, Leonid Libkin, Frank Pfenning: Editorial. ACM Trans. Comput. Log. 3(3): 335-335 (2002)

Marcelo Arenas, Wenfei Fan, Leonid Libkin: What's Hard about XML Schema Constraints? DEXA 2002: 269-278

Michael Benedikt, Leonid Libkin: Tree Extension Algebras: Logics, Automata, and Query Languages. LICS 2002: 203-

Marcelo Arenas, Leonid Libkin: A Normal Form for XML Documents. PODS 2002: 85-96

Marcelo Arenas, Wenfei Fan, Leonid Libkin: On Verifying Consistency of XML Specifications. PODS 2002: 259-270

Stavros S. Cosmadakis, Gabriel M. Kuper, Leonid Libkin: On the orthographic dimension of definable sets. Inf. Process. Lett. 79(3): 141-145 (2001)

Lauri Hella, Leonid Libkin, Juha Nurmonen, Limsoon Wong: Logics with aggregate operators. J. ACM 48(4): 880-907 (2001)

Kenneth A. Ross, Stefano Ceri, Luis Gravano, Per-Åke Larson, Leonid Libkin, Tova Milo: Reminiscences on Influential Papers. SIGMOD Record 30(1): 55-57 (2001)

Leonid Libkin: Logics capturing local properties. ACM Trans. Comput. Log. 2(1): 135-153 (2001)

Leonid Libkin: Expressive Power of SQL. ICDT 2001: 1-21

Michael Benedikt, Leonid Libkin, Thomas Schwentick, Luc Segoufin: A Model-Theoretic Approach to Regular String Relations. LICS 2001: 431-440

Michael Benedikt, Leonid Libkin, Thomas Schwentick, Luc Segoufin: String Operations in Query Languages. PODS 2001

Wenfei Fan, Leonid Libkin: On XML Integrity Constraints in the Presence of DTDs. PODS 2001

Gabriel M. Kuper, Leonid Libkin, Jan Paredaens (Eds.): Constraint Databases. Springer 2000, isbn 3-540-66151-4

Michael Benedikt, Leonid Libkin: Relational queries over interpreted structures. J. ACM 47(4): 644-680 (2000)

Michael Benedikt, Leonid Libkin: Safe Constraint Queries. SIAM J. Comput. 29(5): 1652-1682 (2000)

Guozhu Dong, Leonid Libkin, Limsoon Wong: Local properties of query languages. Theor. Comput. Sci. 239(2): 277-308 (2000)

Leonid Libkin: Logics with counting and local properties. ACM Trans. Comput. Log. 1(1): 33-59 (2000)

Gabriel M. Kuper, Leonid Libkin, Jan Paredaens: Introduction. Constraint Databases 2000: 1-16

Michael Benedikt, Leonid Libkin: Expressive Power: The Finite Case. Constraint Databases 2000: 55-87

Michael Benedikt, Leonid Libkin: Query Safety with Constraints. Constraint Databases 2000: 109-129

Jan Chomicki, Leonid Libkin: Aggregate Languages for Constraint Databases. Constraint Databases 2000: 131-154

Leonid Libkin: Variable Independence, Quantifier Elimination, and Constraint Representations. ICALP 2000: 260-271

Michael Benedikt, Martin Grohe, Leonid Libkin, Luc Segoufin: Reachability and Connectivity Queries in Constraint Databases. PODS 2000: 104-115

Leonid Libkin: Logics Capturing Local Properties. STACS 2000: 217-229

Lauri Hella, Leonid Libkin, Juha Nurmonen: Notions of Locality and Their Logical Characterizations over Finite Models. J. Symb. Log. 64(4): 1751-1773 (1999)

Leonid Libkin: Query languages with arithmetic and constraint databases. SIGACT News 30(4): 41-50 (1999)

Leonid Libkin: Some Remarks on Variable Independence, Closure, and Orthographic Dimension in Constraint Databases. SIGMOD Record 28(4): 24-28 (1999)

Leonid Libkin: Database Principles Column - Introduction. SIGMOD Record 28(4): 29 (1999)

Leonid Libkin: What you can and cannot say in SQL or proving folk theorems in database theory. Proc. 15èmes Journées Bases de Données Avancées, BDA 1999: 425

Leonid Libkin, Limsoon Wong: On the Power of Incremental Evaluation in SQL-Like Languages. DBPL 1999: 17-30

Lauri Hella, Leonid Libkin, Juha Nurmonen, Limsoon Wong: Logics with Aggregate Operators. LICS 1999: 35-44

Leonid Libkin: Logics with Counting, Auxiliary Relations, and Lower Bounds for Invariant Queries. LICS 1999: 316-325

Michael Benedikt, Leonid Libkin: Exact and Approximate Aggregation in Constraint Query. PODS 1999: 102-113

Michael Benedikt, Timothy Griffin, Leonid Libkin: Verifiable Properties of Database Transactions. Inf. Comput. 147(1): 57-88 (1998)

Michael Benedikt, Guozhu Dong, Leonid Libkin, Limsoon Wong: Relational Expressive Power of Constraint Query Languages. J. ACM 45(1): 1-34 (1998)

Leonid Libkin: Models of Approximation in Databases. Theor. Comput. Sci. 190(2): 167-210 (1998)

Leonid Libkin: On Counting Logics and Local Properties. LICS 1998: 501-512

Michael Benedikt, Leonid Libkin: Safe Constraint Queries. PODS 1998: 99-108

Leonid Libkin, Limsoon Wong: Unary Quantifiers, Transitive Closure, and Relations of Large Degree. STACS 1998: 183-193

Leonid Libkin, Bernhard Thalheim (Eds.): Semantics in Databases, Selected Papers from a Workshop, Prague, Czech Republic, 1995. Lecture Notes in Computer Science 1358, Springer 1998, isbn 3-540-64199-8

Leonid Libkin, Limsoon Wong: Query Languages for Bags and Aggregate Functions. J. Comput. Syst. Sci. 55(2): 241-272 (1997)

Timothy Griffin, Leonid Libkin, Howard Trickey: An Improved Algorithm for the Incremental Recomputation of Active Relational Expressions. IEEE Trans. Knowl. Data Eng. 9(3): 508-511 (1997)

Leonid Libkin, Limsoon Wong: Incremental Recomputation of Recursive Queries with Nested Sets and Aggregate Functions. DBPL 1997: 222-238

Leonid Libkin, Limsoon Wong: On the Power of Aggregation in Relational Query Languages. DBPL 1997: 260-280

Leonid Libkin, Juha Nurmonen: Counting and Locality over Finite Structures: A Survey. ESSLLI 1997: 18-50

Guozhu Dong, Leonid Libkin, Limsoon Wong: Local Properties of Query Languages. ICDT 1997: 140-154

Latha S. Colby, Leonid Libkin: Tractable Iteration Mechanisms for Bag Languages. ICDT 1997: 461-475

Leonid Libkin: On the Forms of Locality over Finite Models. LICS 1997: 204-215

Michael Benedikt, Leonid Libkin: Languages for Relational Databases over Interpreted Structures. PODS 1997: 87-98

Leonid Libkin, Limsoon Wong: Semantic Representations and Query Labguages for Or-Sets. J. Comput. Syst. Sci. 52(1): 125-142 (1996)

Stéphane Grumbach, Leonid Libkin, Tova Milo, Limsoon Wong: Query languages for bags: expressive power and complexity. SIGACT News 27(2): 30-44 (1996)

Michael Benedikt, Leonid Libkin: On the Structure of Queries in Constraint Query Languages. LICS 1996: 25-34

Michael Benedikt, Guozhu Dong, Leonid Libkin, Limsoon Wong: Relational Expressive Power of Constraint Query Languages. PODS 1996: 5-16

Michael Benedikt, Timothy Griffin, Leonid Libkin: Verifiable Properties of Database Transactions. PODS 1996: 117-127

Leonid Libkin, Rona Machlin, Limsoon Wong: A Query Language for Multidimensional Arrays: Design, Implementation, and Optimization Techniques. SIGMOD Conference 1996: 228-239

Latha S. Colby, Timothy Griffin, Leonid Libkin, Inderpal Singh Mumick, Howard Trickey: Algorithms for Deferred View Maintenance. SIGMOD Conference 1996: 469-480

Leonid Libkin, Vladimir Gurvich: Trees as semilattices. Discrete Mathematics 145(1-3): 321-327 (1995)

Leonid Libkin, Limsoon Wong: On Representation and Querying Incomplete Information in Databases with Bags. Inf. Process. Lett. 56(4): 209-214 (1995)

Leonid Libkin: Query Language Primitives for Programming with Incomplete Databases. DBPL 1995: 6

Guozhu Dong, Leonid Libkin, Limsoon Wong: On Impossibility of Decremental Recomputation of Recursive Queries in Relational Calculus and SQL. DBPL 1995: 7

Leonid Libkin: Approximation in Databases. ICDT 1995: 411-424

Leonid Libkin: Normalizing Incomplete Databases. PODS 1995: 219-230

Leonid Libkin: A Semantics-based Approach to Design of Query Languages for Partial Information. Semantics in Databases 1995: 170-208

Timothy Griffin, Leonid Libkin: Incremental Maintenance of Views with Duplicates. SIGMOD Conference 1995: 328-339

Elsa L. Gunter, Leonid Libkin: Interfacing HOL90 with a Functional Database Query Language. TPHOLs 1995: 170-185

Leonid Libkin, Limsoon Wong: Conservativity of Nested Relational Calculi with Internal Generic Functions. Inf. Process. Lett. 49(6): 273-280 (1994)

Peter Buneman, Leonid Libkin, Dan Suciu, Val Tannen, Limsoon Wong: Comprehension Syntax. SIGMOD Record 23(1): 87-96 (1994)

Elsa L. Gunter, Leonid Libkin: OR-SML: A Functional Database Programming Language for Disjunctive Information and Its Applications. DEXA 1994: 641-650

Leonid Libkin, Limsoon Wong: New Techniques for Studying Set Languages, Bag Languages and Aggregate Functions. PODS 1994: 155-166

Leonid Libkin: Direct product decompositions of lattices, closures and relation schemes. Discrete Mathematics 112(1-3): 119-138 (1993)

Leonid Libkin, Limsoon Wong: Some Properties of Query Languages for Bags. DBPL 1993: 97-114

Leonid Libkin, Limsoon Wong: Aggregate Functions, Conservative Extensions, and Linear Orders. DBPL 1993: 282-294

Leonid Libkin, Limsoon Wong: Semantic Representations and Query Languages for Or-sets. PODS 1993: 37-48

János Demetrovics, G. Hencsey, Leonid Libkin, Ilya B. Muchnik: On the Interaction Between Closure Operations and Choice Functions with Applications to Relational Database. Acta Cybern. 10(3): 129-140 (1992)

János Demetrovics, G. Hencsey, Leonid Libkin, Ilya B. Muchnik: Normal Form Relation Schemes: A New Characterization. Acta Cybern. 10(3): 141-164 (1992)

János Demetrovics, Leonid Libkin, Ilya B. Muchnik: Functional Dependencies in Relational Databases: A Lattice Point of View. Discrete Applied Mathematics 40(2): 155-185 (1992)

Leonid Libkin: An elementary proof that upper and lower powerdomain constructions commute. Bulletin of the EATCS 48: 175-177 (1992)

Joachim Biskup, János Demetrovics, Leonid Libkin, Ilya B. Muchnik: On Relational Database Schemes Having Unique Minimal Key. Elektronische Informationsverarbeitung und Kybernetik 27(4): 217-225 (1991)

Leonid Libkin: A Relational Algebra for Complex Objects Based on Partial Information. MFDBS 1991: 29-43

Achim Jung, Leonid Libkin, Hermann Puhlmann: Decomposition of Domains. MFPS 1991: 235-258

Georg Gottlob, Leonid Libkin: Investigation on Armstrong relations, dependency inference, and excluded functional dependencies. Acta Cybern. 9(4): 385-402 (1990)

János Demetrovics, Leonid Libkin, Ilya B. Muchnik: Functional Dependencies and the Semilattice of Closed Classes. MFDBS 1989: 136-147