Schemas for Integration and Translation of Structured and Semi-structured Data
ICDT '99 Proceedings of the 7th International Conference on Database Theory
Keyword Searching and Browsing in Databases using BANKS
ICDE '02 Proceedings of the 18th International Conference on Data Engineering
Interconnection semantics for keyword search in XML
Proceedings of the 14th ACM international conference on Information and knowledge management
Parameterized Complexity Theory (Texts in Theoretical Computer Science. An EATCS Series)
Parameterized Complexity Theory (Texts in Theoretical Computer Science. An EATCS Series)
Finding and approximating top-k answers in keyword proximity search
Proceedings of the twenty-fifth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Discover: keyword search in relational databases
VLDB '02 Proceedings of the 28th international conference on Very Large Data Bases
VLDB '04 Proceedings of the Thirtieth international conference on Very large data bases - Volume 30
Keyword proximity search in complex data graphs
Proceedings of the 2008 ACM SIGMOD international conference on Management of data
Learning to create data-integrating queries
Proceedings of the VLDB Endowment
SPARK: A Keyword Search Engine on Relational Databases
ICDE '08 Proceedings of the 2008 IEEE 24th International Conference on Data Engineering
Keyword search in databases: the power of RDBMS
Proceedings of the 2009 ACM SIGMOD International Conference on Management of data
ExQueX: exploring and querying XML documents
Proceedings of the 2009 ACM SIGMOD International Conference on Management of data
Keyword search over relational tables and streams
ACM Transactions on Database Systems (TODS)
From keywords to semantic queries-Incremental query construction on the semantic web
Web Semantics: Science, Services and Agents on the World Wide Web
Finding a minimal tree pattern under neighborhood constraints
Proceedings of the thirtieth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Parameterized Complexity
A personal perspective on keyword search over data graphs
Proceedings of the 16th International Conference on Database Theory
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The task of formulating queries is greatly facilitated when they can be generated automatically from some given data values, schema concepts or both (e.g., names of particular entities and XML tags). This automation is the basis of various database applications, such as keyword search and interactive query formulation. Usually, automatic query generation is realized by finding a set of small tree patterns that contain some given labels. More formally, the computational problem at hand is to find top-k patterns, that is, k minimum-weight tree patterns that contain a given bag of labels, conform to the schema, and are non-redundant. A plethora of systems and research papers include a component that deals with this problem. This paper presents an algorithm for this problem, with complexity guarantees, that allows nontrivial schema constraints and, hence, avoids generating patterns that cannot be instantiated. Specifically, this paper shows that for schemas with certain types of neighborhood constraints, the problem is fixed-parameter tractable (FPT), the parameter being the size of the given bag of labels. As machinery, an adaptation of Lawler-Murty's procedure is developed. This adaptation reduces a top-k problem, over an infinite space of solutions, to a prefix-constrained optimization problem. It is shown how to cast the problem of top-k patterns in this adaptation. A solution is developed for the corresponding prefix-constrained optimization problem, and it uses an algorithm for finding a (single) minimum-weight tree pattern. This algorithm generalizes an earlier work by handling leaf constraints (i.e., which labels may, must or should not be leaves). It all boils down to a reduction showing that, under a language for neighborhood constraints, finding top-k patterns is FPT if a certain variant of exact cover is FPT.