Counterexamples to infinite matroid intersection and packing/covering
What the paper claims, in its own words
Disproves the unrestricted infinite matroid intersection and packing/covering conjectures in ZFC, using two self-dual partitional matroids on a countably infinite ground set. The same examples answer Joó’s partitional-matroid question negatively. They are neither finitary nor cofinitary, so Nash-Williams’ original finitary conjecture remains outside the result.
The plain-language explainer for this entry is still coming.
The original paper
- A Counterexample to the Infinite Matroid Packing/Covering Conjecture (PDF, opens in a new tab) September 24, 2026 Formal proof listed