> I strongly agree with the commentator who likened the hierarchal folder structure to the physical world, it’s a much more direct mapping of how human memory actually works.
But the physical world isn't hierarchical at all. It's spatial. It's much more like a graph than a tree where there are usually multiple paths between any two points.
If you have to pick up your kid from school and stop at the grocery store for milk on the way home from work, you probably do not:
1. Drive to school and get kid.
2. Drive back to work.
3. Drive to grocery story to get milk.
4. Drive back to work.
5. Drive home from work.
Or:
1. Drive to school and get kid.
2. Drive to grocery story to get milk.
3. Drive back to school.
4. Drive back to work.
5. Drive home from work.
If the physical world was hierarchical, all navigation through multiple waypoints would look like this kind of stack pushing and popping.
I'm telling you that all navigation through multiple waypoints DOES usually look like this kind of pushing and popping (just on a massive scale).
So here's a possible day for me:
I work at corporate office A, it's near the highway entrance. I have to pick up my kid - they are at school down the local street heading west. I travel west and pick up my child.
Now I need milk. The closest grocery is back east, just past my office, so I drive back by my office and pull into the grocery.
Then I load up and set off for home. To get there, I need to take the highway to the north, so I head back past my office on that same street and get on the highway using the closest entrance.
I take the highway until I'm home.
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That sure seems like a normal day to me. It's exactly what you said folks would never do, but it's super common. And it's hardly something the modern introduced with cars - there's a cost function to travelling anywhere in the world, and people like to connect using low cost paths - which tends to model a folder hierarchy.
Sure, some routes end up being tree-like, because trees are a subset of graphs. But just as often you see waypoints like:
1. Leave the office.
2. Drive to the grocery store.
3. Drive to school.
4. Drive home.
Where there is no backtracking between them.
> And it's hardly something the modern introduced with cars - there's a cost function to travelling anywhere in the world, and people like to connect using low cost paths - which tends to model a folder hierarchy.
A tree doesn't minimize the cost for any given trip or for the aggregate cost of all trips between pairs of points. Because a tree has only a single path between any two points, it has the highest possible aggregate trip cost for all possible trips while still being connected.
What it does minimize is the cost of building and maintaining the paths. Since there is only a single path between any pair of points, it has the fewest redundant edges. If you were tasked with building a road network for a country and your sole goal was to minimize the amount of concrete used, you'd build a tree.
If your only goal was to minimize the aggregate distance all travellers took, you'd build a fully-connected graph where every pair of destinations has a dedicated road.
In practice, road networks are designed to minimize both road maintenance costs and drive time and balance those opposing forces. The result is more connected than a tree but less connected than a complete graph, something like a semilattice.
But the physical world isn't hierarchical at all. It's spatial. It's much more like a graph than a tree where there are usually multiple paths between any two points.
If you have to pick up your kid from school and stop at the grocery store for milk on the way home from work, you probably do not:
1. Drive to school and get kid.
2. Drive back to work.
3. Drive to grocery story to get milk.
4. Drive back to work.
5. Drive home from work.
Or:
1. Drive to school and get kid.
2. Drive to grocery story to get milk.
3. Drive back to school.
4. Drive back to work.
5. Drive home from work.
If the physical world was hierarchical, all navigation through multiple waypoints would look like this kind of stack pushing and popping.