One of my favourite displays of the 3-dimensional associahedron is the following, taken from the John Baez post More Secrets of the Associahedra. It indicates the automorphism group: the dihedral group of a 6-gon.
Associahedron/hexagon images can be found on the web, in particular on the John Baez posts
The relation between polygon triangulations and associahedra is described in
See chapter 7 on secondary polytopes, pages 237 ff.
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