DOAJ Open Access 2020

The topology of the external activity complex of a matroid

Federico Ardila Federico Castillo Jose Samper

Lihat Sumber DOI

Abstrak

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 <ext/int on M provides a shelling of Act<(M). We also show that every linear extension of Las Vergnas's internal order <int on M provides a shelling of the independence complex IN(M). As a corollary, Act<(M) and M have the same h-vector. We prove that, after removing its cone points, the external activity complex is contractible if M contains U3,1 as a minor, and a sphere otherwise.

Topik & Kata Kunci

Mathematics

Penulis (3)

Federico Ardila

Federico Castillo

Jose Samper

Format Sitasi

APA MLA BibTeX

Ardila, F., Castillo, F., Samper, J. (2020). The topology of the external activity complex of a matroid. https://doi.org/10.46298/dmtcs.6355

Akses Cepat

Lihat di Sumber doi.org/10.46298/dmtcs.6355

Informasi Jurnal

Tahun Terbit: 2020
Sumber Database: DOAJ
DOI: 10.46298/dmtcs.6355
Akses: Open Access ✓