Arrow in models of composite systems tend to have the oppsite directions in programming languages (both OO & Functional) and relational models. In programing landuages the parent knows about its children while in relational models the children tend to know about their parent.
There are several reasons for this
relational models do not support multivalued attributes
it makes it easy to grow a tree nondestructively in the relational model
relational models have indexes andbult in operations like join that make it possible to find all the descendants of a node even when the arrows point upwards.
Arrow in models of composite systems tend to have the oppsite directions in programming languages (both OO & Functional) and relational models. In programing landuages the parent knows about its children while in relational models the children tend to know about their parent. There are several reasons for this
What is the preferred way in Catlab?