Leonid Libkin

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  • Formal Semantics of the Language Cypher

    Cypher is a query language for property graphs. It was originally designed and implemented as part of the Neo4j graph database, and it is currently used in a growing number of commercial systems, industrial applications and research projects. In this work, we provide denotational semantics of the core fragment of the read-only part of Cypher, which features in particular pattern matching, filtering, and most relational operations on tables.

    02/27/2018 ∙ by Nadime Francis, et al. ∙ 0 share

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  • Data Context Informed Data Wrangling

    The process of preparing potentially large and complex data sets for further analysis or manual examination is often called data wrangling. In classical warehousing environments, the steps in such a process have been carried out using Extract-Transform-Load platforms, with significant manual involvement in specifying, configuring or tuning many of them. Cost-effective data wrangling processes need to ensure that data wrangling steps benefit from automation wherever possible. In this paper, we define a methodology to fully automate an end-to-end data wrangling process incorporating data context, which associates portions of a target schema with potentially spurious extensional data of types that are commonly available. Instance-based evidence together with data profiling paves the way to inform automation in several steps within the wrangling process, specifically, matching, mapping validation, value format transformation, and data repair. The approach is evaluated with real estate data showing substantial improvements in the results of automated wrangling.

    11/22/2018 ∙ by Martin Koehler, et al. ∙ 0 share

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