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Birigidity maximality conjecture

Prove that, for all n1,n2,d1,d2, the generic (d1,d2)-birigidity matroid R_{d1,d2}(K_{n1,n2}) is the unique maximal matroid under the weak order among all abstract (d1,d2)-birigidity matroids on E(K_{n1,n2}).

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Background

Abstract birigidity extends the gluing axioms to bipartite graphs. The conjecture mirrors Graver’s maximality conjecture but in the birigidity setting. It is known when d1=1 or d2=1 (scene analysis) and when one side is within 3 of full rank via dual uniform matroid products; the general case is open.

A solution would parallel rigidity’s structure theory for bipartite frameworks and inform low-rank matrix completion.

References

Conjecture [Birigidity maximality conjecture]\nLet $n_1,n_2, d_1, d_2$ be positive integers. Then the generic $(d_1,d_2)$-rigidity matroid of $K_{n_1,n_2}$ is the unique maximal matroid in the family of abstract $(d_1,d_2)$-birigidity matroids of $K_{n_1,n_2}$.

Rigidity of Graphs and Frameworks: A Matroid Theoretic Approach (2508.11636 - Cruickshank et al., 29 Jul 2025) in Birigidity