The topology of the external activity complex of a matroid

Federico Ardila (1, 2) , Federico Castillo (3) , Jose Alejandro Samper (4)

1 SFSU - San Francisco State University
2 UNIANDES - Universidad de los Andes [Bogota]
3 UC Davis - University of California [Davis]
4 University of Washington [Seattle]

We prove that the external activity complex Act<(M) of a matroid is shellable. In fact, we show that every linear extension of Las Vergnas's external/internal order

Domaines: Combinatoire [math.CO]

Federico Ardila, Federico Castillo, Jose Alejandro Samper. The topology of the external activity complex of a matroid. 28-th International Conference on Formal Power Series and Algebraic Combinatorics, Simon Fraser University, Jul 2016, Vancouver, Canada. ⟨10.46298/dmtcs.6355⟩. ⟨hal-02173754⟩