Cordovil–Moreira cyclic ordering conjecture for two matroid bases

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Let MM be a finite loopless matroid of rank rr, and let B={b1,…,br}B=\{b_1,\dots,b_r\} and B′={b1′,…,br′}B'=\{b'_1,\dots,b'_r\} be two bases of MM. A cyclic ordering is an ordering considered cyclically, so that every block of rr consecutive elements is required to be a base. Cordovil–Moreira's conjecture. There are permutations (bπ(1),…,bπ(r))(b_{\pi(1)},\ldots,b_{\pi(r)}) of the elements of BB and (bπ′(1)′,…,bπ′(r)′)(b'_{\pi'(1)},\ldots,b'_{\pi'(r)}) of the elements of B′B' such that the combined sequence (bπ(1),…,bπ(r),bπ′(1)′,…,bπ′(r)′)(b_{\pi(1)},\ldots,b_{\pi(r)},b'_{\pi'(1)},\ldots,b'_{\pi'(r)}) is a cyclic ordering in which every rr cyclically consecutive elements form a base. This conjecture is known for graphical matroids, but remains open for general matroids.

References

Primary source

Jan van den Heuvel and Stéphan Thomassé, “Cyclic Orderings and Cyclic Arboricity of Matroids”, arXiv:0912.2929 (2011).

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