Product Sets and Projection Mappings

Suppose we have

SET COM (Food, Agric, Serv) ;

SET SOURCE (dom, imp) ; ! domestic or imports !

We can write:

SET S4 = COM x SOURCE ;

The elements of S4 are

Food_dom, Agric_dom, Serv_dom, Food_imp, Agric_imp, Serv_imp .

If needed, GEMPACK will truncate names so that combined names still have no more than 12 characters. Note elements of the first set vary faster. COM and SOURCE are automatically subsets of S4. We can also write:

MAPPING (PROJECT) S4toSOURCE from S4 to SOURCE ;

which would map Food_dom to dom, Agric_imp to imp, and so on.

URL of this topic: www.copsmodels.com/webhelp/tabmate/hc_productsets.htm

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