Quantity¶
Definition¶
The «Quantity» construct is used to represent rigid concepts that provide an identity principle for their instances. A «Quantity» represent uncountable things, like Water, Clay, or Beer. It represents a maximally topologically connected amount of matter. Quantities only have other quantities as parts (see the «SubQuantityOf» relation for more details about members of collections). Here are some examples:
![Quantity examples](../../../_images/ontouml_quantity-examples.png)
An easy way to decide whether a concept is a quantity or not, as yourself this: if you physically divide an instance of ‘x’ in two parts, are the resulting individuals two new instances of x? What if you divide another 5 or 10 times? If the answer is always yes, ‘x’ is a Quantity. To exemplify, let’s think about an pile of sand. If you divide the pile in two, you now have to new piles of sand, right? What if you do that again for each remaining part? We would have 4 piles of sand.
![Tannin heap](../../../_images/Tannin_heap.jpeg)
As the other identity provider stereotypes («Kind», «Collective», «Relator» and «Mode»), a Quality can be specialized by subkinds, phases and roles, as well as generalized by mixins and categories.
![Quantity application 1](../../../_images/ontouml_quantity-application-1.png)
Constraints¶
C1: A «Quantity» cannot have an identity provider («Kind», «Collective», «Quantity», «Relator», «Mode» and «Quantity») as its direct or indirect super-type.
![Quantity forbidden 1](../../../_images/ontouml_quantity-forbidden-1.png)
C2: A «Quantity» cannot have types that inherit identity («Subkind», «Role» and «Phase») as its direct or indirect super-types.
![Quantity forbidden 2](../../../_images/ontouml_quantity-forbidden-2.png)
C3: A «Quantity» cannot have types that aggregate individuals with different identity principles («Category», «RoleMixin» and «Mixin») as its direct or indirect subtypes.
![Quantity forbidden 3](../../../_images/ontouml_quantity-forbidden-4.png)
C4: As a rigid type, a «Quantity» cannot have any anti-rigid type («Role», «RoleMixin» and «Phase») as its direct or indirect super-type.
![Quantity forbidden 4](../../../_images/ontouml_quantity-forbidden-3.png)
Common questions¶
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Examples¶
Todo
To be added …