Strange mappings

A mapping specifies a source set and a target set; and, for each member of the source set, the corresponding element in the target set. Normally:

(a) the source set has more elements than the target set.

(b) the mapping is onto: each member of the target set is mapped to by at least one member of the source set.

However, ViewHAR does not insist on these conditions, although warnings may be issued.

(a) Let REGALFA be the set of R regions sorted alphabetically, and REGSIZ be the same set of regions ordered by land area. You could could permute or reorder a vector size R by remapping from REGALFA to REGSIZ.

(b) Let REG be the set of nations, COM the set of goods, and the mapping MAINEXP (from REG to COM) shows for each region the main export good. Probably, some goods are not the main export of any region: MAINEXP is not onto.

URL of this topic: www.copsmodels.com/webhelp/viewhar/hc_strangemap.htm

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