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Re: Nested Sets vs. Nested Intervals

From: <amado.alves_at_netcabo.pt>
Date: 10 Nov 2005 19:02:24 -0800
Message-ID: <1131674470.239615.88020@g43g2000cwa.googlegroups.com>


Mneson is not Codasyl nor OQL based on the descriptions I have of those.

I believe the Mneson Calculus is an algebra. I'm still working on it. Example laws:

T ({x1, x2, ...}) = T({x1}) U T({x2}) U ...
T ({}) = {}
T (XUY) = T(X) U T(Y)
T (X^Y) = T(X) ^ T(Y)

Etc.

Conditions on values are made possible by introducing value ranges, set of values expressed in a compact way, typically as an interval or a bound. Querying for employees earning less than 40,000:

T (Employees) ^ S (S (T (T (Salary)) ^ RangeForLessThan (40'000)))

Of course query optimization would kick in here, and that's the main purpose of having the algebra. Received on Thu Nov 10 2005 - 21:02:24 CST

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