Retroactive data structures

Erik D. Demaine, John Iacono, Stefan Langerman

    Research output: Contribution to journalArticlepeer-review


    We introduce a new data structuring paradigm in which operations can be performed on a data structure not only in the present, but also in the past. In this new paradigm, called retroactive data structures, the historical sequence of operations performed on the data structure is not fixed. The data structure allows arbitrary insertion and deletion of operations at arbitrary times, subject only to consistency requirements. We initiate the study of retroactive data structures by formally defining the model and its variants. We prove that, unlike persistence, efficient retroactivity is not always achievable. Thus, we present efficient retroactive data structures for queues, doubly ended queues, priority queues, union-find, and decomposable search structures.

    Original languageEnglish (US)
    Article number1240236
    JournalACM Transactions on Algorithms
    Issue number2
    StatePublished - May 1 2007


    • History
    • Persistence
    • Point location
    • Rollback
    • Time travel

    ASJC Scopus subject areas

    • Mathematics (miscellaneous)


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