Re: The Practical Benefits of the Relational Model

> Therefore, the pairs of dual relational operations are:

> 1. Intersection is dual to Cartesian Product.
> 2. Union is dual to Naisetrac Product.
> 3. Selection is dual to Projection.

Correction:

Intersection = Cartesian Product * Selection Union = Naisetrac Product * Projection

Therefore:

1. Intersection is dual to Union (as in the set theory;-)
2. Cartesian Product is dual to Naisetrac Product
3. Selection is dual to Projection