T x T -> D
but
T1 x T2 != T2 x T1
D -> T x T
So globally, there is an isomorphism
T x T <-> D
- with an op
+
(associative but non-commutative)
D + D -> D
- an id element
E
D + E = E + D = D
To be complete:
- T represents the set of RoseTrees
- D represents a Diff between 2 rosetrees