Zobrazeno 1 - 4
of 4
pro vyhledávání: '"Seyed Hadi Afzali Borujeni"'
Publikováno v:
Order. 37:299-309
By considering the number of maximal chains going through each element of an arbitrary poset, we prove an extension of Erdős’s generalisation of Sperner’s Theorem, together with a partial converse. By considering the number of maximal chains bet
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::188ef05924d644acf710e5179070684b
https://doi.org/10.1007/s11083-019-09506-2
https://doi.org/10.1007/s11083-019-09506-2
Publikováno v:
Discrete Applied Mathematics. 209:2-10
A gammoid is a matroid defined using linkability of vertex sets in a (possibly infinite) digraph. Related types of matroids are strict gammoids and transversal matroids, three aspects of which will be considered as follows.First, we investigate the i
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::6e0cf0b82ad9c465b8e0b4ea619f5e51
https://doi.org/10.1016/j.dam.2015.07.030
https://doi.org/10.1016/j.dam.2015.07.030
Publikováno v:
The Electronic Journal of Combinatorics. 22
Finite strict gammoids, introduced in the early 1970's, are matroids defined via finite digraphs equipped with some set of sinks: a set of vertices is independent if it admits a linkage to these sinks. In particular, an independent set is maximal (i.
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::c9e12ebb4d8e493aa31ff2bc90834e34
https://doi.org/10.37236/4181
https://doi.org/10.37236/4181
This sequel to our paper (Infinite gammoids, 2014) considers minors and duals of infinite gammoids. We prove that a class of gammoids definable by digraphs not containing a certain type of substructure, called an outgoing comb, is minor-closed. Also,
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::bebf4445fbdbbce300ab4305e8276425
