2 problems

For a matroid $M$, a circuit-cocircuit intersection (CCI) is a subset of its ground set that is the intersection of a circuit and a cocircuit. Oxley's circuit-cocircuit intersectio…

A circuit-cocircuit intersection (CCI) is a subset of a matroid's ground set that is the intersection of a circuit and a cocircuit. A CCI-envelope is a matroid that contains a CCI…