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  1. #1
    Join Date
    Mar 2004

    Post reflexivity rule in armstrongs axioms (was "Please say you can help me")

    Hi does any bright spak out there know why this reflexivity rule in armstrongs axioms returns at most 1 tuple??
    You dont need to know what reflexivity or armstrongs axioms are, i just need to know why this returns at most one tuple.
    The 'X' is a subset of a Schema 'R'. i.e its a column.
    please see the attached image "reflexivity.jpg"
    i think the pie symbol means 'project'
    the circular symbol means select
    and r is a relation.
    please dont quote me on the above 3 lines
    best wishes for the new year,
    Attached Thumbnails Attached Thumbnails reflexivity.jpg  

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