Notes for Sale-Price:
- We specifically chose not to define the price as the `value'
of the PRODUCT, because value is relative, the price is the
actual thing exchanged (usually money).
Slots on function Sale-Price:
- Arity: 2
the Good-Service-or-Money that is agreed to be exchanged by
the ACTUAL-CUSTOMER with the SALE-VENDOR in a SALE.
- Domain: Sale
- Instance-Of: Binary-Relation, Function, Relation, Set
- Range: Good-Service-Or-Money
Other Related Axioms for Sale-Price:
(Inherited-Facet-Value Minimum-Slot-Cardinality Sale Sale-Price 0)