Distance-set rigidity conjecture for finite GH-spaces generated by labeled trees

Let i=1,2i=1,2 and let Ti=Ti(li)T_i=T_i(l_i) be finite labeled trees with non-degenerate labelings li:V(Ti)R+l_i:V(T_i)\to\mathbb{R}^+. Suppose that (V(T1),dl1)(V(T_1),d_{l_1}) and (V(T2),dl2)(V(T_2),d_{l_2}) are GH\bf GH-spaces. For a space (V(Ti),dli)(V(T_i),d_{l_i}), let D(V(Ti))D(V(T_i)) denote its distance set. Distance-set rigidity conjecture. The following statements are equivalent:

  1. D(V(T1))=D(V(T2))D(V(T_1))=D(V(T_2)).
  2. (V(T1),dl1)(V(T_1),d_{l_1}) and (V(T2),dl2)(V(T_2),d_{l_2}) are isometric.

The implication from isometry to equality of distance sets is immediate, and the converse is known when both trees have at most three vertices; the general case remains open.

Sources & referencesView supporting material

Primary source

Oleksiy Dovgoshey and Olga Rovenska, “The Gomory-Hu inequality and trees”, arXiv:2604.18400 (2026).

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