“…The pentagram map, T 2 , is one of the best known discrete completely integrable system. See for instance, [1], [2], [3], [8], [9], [10], [11], [12], [14], [15], [21], [22]. The Pentagram Rigidity Conjecture would be a statement about the global topology of an abelian foliation associated to a completely integrable system if the map T 3 were known to be completely integrable.…”