Coarea
The complement of the area within the enclosing triangle.
Coarea(path)
Details
- Defined over `DyckPath` as an expression in `_x`, evaluated by compute-engine — the definition IS the implementation.
- Takes a `DyckPath` and nothing else — it reads values against their positions, or walks the orbits, so it needs the bijection. Applying it to a bare list is a type error, not a wrong answer.
- Defined against the n(n+1)/2 triangle for a path of 2n steps.