Theoretical analysis reveals orderable cographic matroids from projective-plane triangulations, disproving Crenshaw–Oxley Conjecture 4.
We prove that the cographic matroid of the 1-skeleton of every finite simplicial triangulation of the real projective plane is orderable. Starting from the six-vertex triangulation with 1-skeleton K6 and repeatedly applying stellar subdivision gives infinitely many 3-connected, regular, binary, non-graphic, orderable matroids, providing counterexamples to Crenshaw--Oxley Conjecture 4. Status: Public Beta; internally verified candidate proof; external review pending.
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