We explore a problem of Frankl (1989). A family ~ of subsets of {1, 2, ..., m} is said to have trace Kk if there is a subset SC\_{1,2 ..... m} with IS] = k so that {FNSIF C .~} yields all 2 k possible subsets. Frankl (1989) conjectured that a family ~ which is an antichain (in poser given by C\_ ord
The VC-Dimension of Sperner Systems
β Scribed by G. Greco
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- English
- Weight
- 119 KB
- Volume
- 87
- Category
- Article
- ISSN
- 0097-3165
No coin nor oath required. For personal study only.
β¦ Synopsis
A family F of subsets of a finite set X shatters a set D X, if the intersections of the members of F with D coincide with the power set of D. The maximum size of a set shattered by F is the VC-dimension (or density) of the system. P. Frankl (1983, J. Combin. Theory Ser. A 34, 41 45) investigates the behavior of the maximum size of a Sperner family having bounded VC-dimension and conjectures that if F 2 [m] is a Sperner family of VC-dimension less than 0mΓ2 if m 7). This bound is shown to be tight for infinitely many values of m with explicit constructions.
1999 Academic Press
1. TERMINOLOGY AND NOTATION
A set system F 2 [m] , [m]=[1, 2, ..., m], is a Sperner system if for every two members of the system none contains the other (i.e., F is an antichain in the boolean lattice). A chain is a sequence of sets A i [m], 0 i n such that
A chain is complete if n=m and |A i | =i for every 0 i m.
If D is a subset of [m] the trace of F on D is
If F| D =2 D we say that F shatters D. The maximum size of a set shattered by F is the Vapnik Chervonenkis dimension (VC-dimension) of the system [10] and it is denoted by d VC (F). We recall that for every pair of positive
π SIMILAR VOLUMES
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Let X be an n-element set and 2' be the family of subsets of X. If&C c 2' such that for any K. K\_ F .%'" K. f K\_ it-dim K. ct K. then Wr is ca!!pd a Sn~rtwr wstem Let \_M be 8~ ,+\_ x g \_\_l'\_\_L-~" '\_\_I , \_\_' \_\_\_\_=\_\_ \_\_ \_\_I i \_\_' \_ .
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