Title
A Meshalkin theorem for projective geometries
Abstract
Let M be a family of sequences (a1,..., ap) where each ak is a flat in a projective geometry of rank n (dimension n- 1) and order q, and the sum of ranks, r(a1)+ ... + r(ap), equals the rank of the join a1 ∨ ... ∨ ap. We prove upper bounds on |M| and corresponding LYM inequalities assuming that (i) all joins are the whole geometry and for each k the set of all ak's of sequences in M contains no chain of length l, and that (ii) the joins are arbitrary and the chain condition holds for all k. These results are q-analogs of generalizations of Meshalkin's and Erdös's generalizations of Sperner's theorem and their LYM companions, and they generalize Rota and Harper's q-analog of Erdös's generalization.
Year
DOI
Venue
2003
10.1016/S0097-3165(03)00049-9
J. Comb. Theory, Ser. A
Keywords
Field
DocType
primary 05d05,rank n,meshalkin's theorem,r -chain-free,sperner's theorem,r -family,chain condition,length l,upper bound,dimension n,lym companion,lym inequality,order q,projective geometry,secondary 06a07,corresponding lym inequality,antichain,whole geometry,51e20,meshalkin theorem,projective geometries
Discrete mathematics,Combinatorics,Antichain,Joins,Sperner's theorem,Projective geometry,Generalization,Mathematics,Projective test
Journal
Volume
Issue
ISSN
102
2
Journal of Combinatorial Theory, Series A
Citations 
PageRank 
References 
1
2.40
1
Authors
2
Name
Order
Citations
PageRank
Matthias Beck1348.39
T. Zaslavsky229756.67