Gammoids, pseudomodularity and flatness degree
The electronic journal of combinatorics, Tome 22 (2015) no. 1
We introduce the concept of flatness degree for matroids, as a generalization of submodularity. This represents weaker variations of the concept of flatness which characterize strict gammoids for finite matroids. We prove that having flatness degree 3, which is the smallest non-trivial flatness degree, implies pseudomodularity on the lattice of flats of the matroid. We show however an example of a gammoid for which the converse is not true. We also show examples of gammoids with each possible flatness degree. All of this examples show that pseudomodular gammoids are not necessarily strict.
DOI :
10.37236/4671
Classification :
05B35
Mots-clés : matroid theory, gammoids, pseudomodularity, directed graphs
Mots-clés : matroid theory, gammoids, pseudomodularity, directed graphs
Affiliations des auteurs :
Jorge Alberto Olarte  1
@article{10_37236_4671,
author = {Jorge Alberto Olarte},
title = {Gammoids, pseudomodularity and flatness degree},
journal = {The electronic journal of combinatorics},
year = {2015},
volume = {22},
number = {1},
doi = {10.37236/4671},
zbl = {1308.05032},
url = {http://geodesic.mathdoc.fr/articles/10.37236/4671/}
}
Jorge Alberto Olarte. Gammoids, pseudomodularity and flatness degree. The electronic journal of combinatorics, Tome 22 (2015) no. 1. doi: 10.37236/4671
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