A calculus for complex objects
PODS '86 Proceedings of the fifth ACM SIGACT-SIGMOD symposium on Principles of database systems
Set operations in a data model supporting complex objects
EDBT '90 Proceedings of the 2nd international conference on extending database technology: Advances in Database Technology
Extending the relational algebra to capture complex objects
VLDB '89 Proceedings of the 15th international conference on Very large data bases
Schema equivalence in heterogeneous systems: bridging theory and practice
Information Systems - Special issue on extending database technology
Schema integration and transaction management for multidatabases
Information Sciences—Informatics and Computer Science: An International Journal
Data on the Web: from relations to semistructured data and XML
Data on the Web: from relations to semistructured data and XML
The power of languages for the manipulation of complex values
The VLDB Journal — The International Journal on Very Large Data Bases
Theoretical Aspects of Schema Merging
EDBT '92 Proceedings of the 3rd International Conference on Extending Database Technology: Advances in Database Technology
A Relation Merging Technique for Relational Databases
Proceedings of the Eighth International Conference on Data Engineering
A Structure Based Schema Integration Methodology
ICDE '95 Proceedings of the Eleventh International Conference on Data Engineering
Merging Inheritance Hierarchies for Database Integration
COOPIS '98 Proceedings of the 3rd IFCIS International Conference on Cooperative Information Systems
Using Conceptual Graph Theory to Support Schema Integration
ER '93 Proceedings of the 12th International Conference on the Entity-Relationship Approach: Entity-Relationship Approach
Integration of Heterogeneous Object Schemas
ER '93 Proceedings of the 12th International Conference on the Entity-Relationship Approach: Entity-Relationship Approach
Operations and Implementation of Complex Objects
Proceedings of the Third International Conference on Data Engineering
Efficient Complex Query Support for Multiversion XML Documents
EDBT '02 Proceedings of the 8th International Conference on Extending Database Technology: Advances in Database Technology
Rondo: a programming platform for generic model management
Proceedings of the 2003 ACM SIGMOD international conference on Management of data
Clustering semantically related classes in a heterogeneous multidatabase system
Information Sciences: an International Journal
Semantic integration: a survey of ontology-based approaches
ACM SIGMOD Record
XML application schema matching using similarity measure and relaxation labeling
Information Sciences: an International Journal
An ontology based approach to the integration of entity-relationship schemas
Data & Knowledge Engineering - Special issue: ER 2004
Computers in Industry - Special issue: Collaborative environments for concurrent engineering
Combining schema and instance information for integrating heterogeneous data sources
Data & Knowledge Engineering
Matching large schemas: Approaches and evaluation
Information Systems
FCA-MERGE: bottom-up merging of ontologies
IJCAI'01 Proceedings of the 17th international joint conference on Artificial intelligence - Volume 1
RDFSculpt: managing RDF schemas under set-like semantics
ESWC'05 Proceedings of the Second European conference on The Semantic Web: research and Applications
A survey of schema-based matching approaches
Journal on Data Semantics IV
Integrating and exchanging XML data using ontologies
Journal on Data Semantics VI
Management of evolving semantic grid metadata within a collaborative platform
Information Sciences: an International Journal
Element similarity measures in XML schema matching
Information Sciences: an International Journal
Rough set theory applied to lattice theory
Information Sciences: an International Journal
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The Semantic Web is the next step of the current Web where information will become more machine-understandable to support effective data discovery and integration. Hierarchical schemas, either in the form of tree-like structures (e.g., DTDs, XML schemas), or in the form of hierarchies on a category/subcategory basis (e.g., thematic hierarchies of portal catalogs), play an important role in this task. They are used to enrich semantically the available information. Up to now, hierarchical schemas have been treated rather as sets of individual elements, acting as semantic guides for browsing or querying data. Under that view, queries like ''find the part of a portal catalog which is not present in another catalog'' can be answered only in a procedural way, specifying which nodes to select and how to get them. For this reason, we argue that hierarchical schemas should be treated as full-fledged objects so as to allow for their manipulation. This work proposes models and operators to manipulate the structural information of hierarchies, considering them as first-class citizens. First, we explore the algebraic properties of trees representing hierarchies, and define a lattice algebraic structure on them. Then, turning this structure into a boolean algebra, we present the operators S-union, S-intersection and S-difference to support structural manipulation of hierarchies. These operators have certain algebraic properties to provide clear semantics and assist the transformation, simplification and optimization of sequences of operations using laws similar to those of set theory. Also, we identify the conditions under which this framework is applicable. Finally, we demonstrate an application of our framework for manipulating hierarchical schemas on tree-like hierarchies encoded as RDF/s files.