A City is not a Tree
More diagrams in Figma
# Why graphs instead of trees
Both the tree and the semilattice are ways of thinking about how a large collection of many small systems goes to make up a large and complex system. More generally, they are both names for structures of sets.
For the human mind, the tree is the easiest vehicle for complex thoughts. But the city is not, cannot and must not be a tree. The city is a receptacle for life. If the receptacle severs the overlap of the strands of life within it, because it is a tree, it will be like a bowl full of razor blades on edge, ready to cut up whatever is entrusted to it. In such a receptacle life will be cut to pieces. If we make cities which are trees, they will cut our life within to pieces.
# Urban Planning
Columbia, Maryland: Neighbourhoods, in clusters of five, form ‘villages’. Transportation joins the villages into a new town. The organization is a tree.
Hilberseimer’s book The Nature of Cities: He describes the fact that certain Roman towns had their origin as military camps. The symbol is apt, for, of course, the organization of the army was designed precisely in order to create discipline and rigidity.
See more in the note on Urban planning
# Why graphs are hard to visualize
The example the article used was to try and an orange, a watermelon, a football and a tennis ball. How will you keep them in your mind, in your mind’s eye? However you do it, you will do it by grouping them. Maybe two fruits and two sports balls together. In doing so, you construct a tree structure. Maybe you group it by size, two small spheres and two large spheres. This constructs another tree. But try as hard as you like, two trees combined form a semilattice. It is very difficult to hold a semilattice in your head.
Maybe this is where tools like knowledge graphs come in. Allow us to better visually explore these graph relations and allow us to capture more complex relations in things
Regular note taking like Notion is hierarchical and linear → its a tree Graph representations like Roam Research, Obsidian allow us to make non-obvious non-hierarchical connections between concepts