Close the Edge-Count Reconstruction Sample-Complexity Gap

Close the gap between the $O(n^3)$ upper bound and the $Omega(n^2)$ lower bound for the number of vertex-deletion traces required to reconstruct the number of edges of an $n$-vertex graph.

Background

For recovering the number of edges, the paper proves an O(n3)O(n^3) upper bound and an Omega(n2)Omega(n^2) lower bound on the required number of degree-sequence traces. The bounds differ by a factor of order nn.

The authors explicitly classify closing this gap as an open problem related to graph trace reconstruction.

References

There are several other open problems related to the graph trace reconstruction. One could also try to close the gap between the $O(n3)$ upper and $\Omega(n2)$ lower bounds for size reconstruction.

Degree Sequence Reconstruction from Subgraph Traces  (2609.09397 - Gandikota et al., 8 Sep 2026) in Section 5, Conclusion, Open Problems