Spotted this in an alleyway, and at first I thought it was a utility worker who had used this cement guard as a notepad. On closer inspection, it seems like a formula? For a hyperbola?
Not really sure what to make of this. Part of me thinks that if it’s writing in a public area, it’s vandalism. And another part of me wonders if this is just someone trying to be helpful, a bit like jotting down the quadratic equation, just in case someone might need some reminding in the future.