OFFSET
0,3
COMMENTS
See link for software to generate the sequence. The next item (for n=8) should be roughly 2^78 and seems hopeless without more mathematics.
Antimatroids are a subset of greedoids, usually defined either in terms of set systems, as David Eppstein does in his tree searches, or in terms of formal languages. The two are equivalent, as discussed in Kempner and Levit. - Jonathan Vos Post, Jun 20 2006
LINKS
D. Eppstein, Reverse search for antimatroids.
Yulia Kempner, Vadim E. Levit, Correspondence between two antimatroid algorithmic characterizations, arXiv:math/0307013 [math.CO], 2003.
P. Uznanski Enumeration of antimatroids
EXAMPLE
The three antimatroids on the two items 0 and 1 are (a) {},{0},{0,1}, (b) {},{1},{0,1} and (c) {},{0},{1},{0,1}.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
David Eppstein, Jun 19 2006
EXTENSIONS
Term for n=6 added based on a computer search by Przemysław Uznański - David Eppstein, Feb 26 2013
Term for n=7 added by Przemyslaw Uznanski, computed by Przemysław Uznański and Michał Bartoszkiewicz, Apr 19 2013
STATUS
approved