Can node graphs have cycles?

[Pharap]

I was reading the Minecraft Wiki article about Brigadier which states:

/execute run redirects to the root node of the vanilla command dispatcher

Which implies that the command 'tree' can have cycles (which would mean that it's technically not a tree, which must be acyclic, but in in fact a rooted unidirected graph).

So I just wanted to clarify whether or not what the Wiki claims is correct, and whether it is technically possible for node graphs to have cycles (perhaps even back to the root node) or whether Minecraft does something special to achieve execute's recursive/cyclic functionality.

(If that's the case, it may be worth clarifying this in the README.md.)

[Pokechu22]

https://wiki.vg/Command_Data says:

When including redirects, this structure is a directed graph that may include cycles (e.g. consider /execute run execute run execute ...). When excluding redirects, the structure no longer contains cycles but may still not be a tree, as a node may have multiple parents.

This image (PNG, 1.5 MB, 2179 by 14448 - mobile users avoid this) from 18w22c indicates redirects with a dashed line and normal children with a solid line.

Note that wiki.vg is documenting the format used over the network protocol, which may be slightly different from what you expect.