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,