[om-list] Cardinality Errata

[Mark Butler]

Correction to my last posting:

  Rules 1 and 2, cardinality addition and subtraction, respectively 
should read "order set to greatest", not "order adds if type equal, 
otherwise set to greatest".   A good way to think of this is class R1 
for lengths, R2 for areas, R3 for volumes - or in other words that all 
lengths, areas, and volumes have infinite cardinality of three different 
orders, we just factor the infinity out into the units for computational 
convenience.

- Mark