{ "id": "1105.3862", "version": "v2", "published": "2011-05-19T13:13:04.000Z", "updated": "2011-07-23T10:36:31.000Z", "title": "A BK inequality for randomly drawn subsets of fixed size", "authors": [ "J. van den Berg", "J. Jonasson" ], "comment": "Revised version for PTRF. Equation (13) corrected. Several, mainly stylistic, changes; more compact", "categories": [ "math.PR" ], "abstract": "The BK inequality (\\cite{BK85}) says that,for product measures on $\\{0,1\\}^n$, the probability that two increasing events $A$ and $B$ `occur disjointly' is at most the product of the two individual probabilities. The conjecture in \\cite{BK85} that this holds for {\\em all} events was proved by Reimer (cite{R00}). Several other problems in this area remained open. For instance, although it is easy to see that non-product measures cannot satisfy the above inequality for {\\em all} events,there are several such measures which, intuitively, should satisfy the inequality for all{\\em increasing} events. One of the most natural candidates is the measure assigning equal probabilities to all configurations with exactly $k$ 1's (and probability 0 to all other configurations). The main contribution of this paper is a proof for these measures. We also point out how our result extends to weighted versions of these measures, and to products of such measures.", "revisions": [ { "version": "v2", "updated": "2011-07-23T10:36:31.000Z" } ], "analyses": { "subjects": [ "60C05", "60K35" ], "keywords": [ "randomly drawn subsets", "bk inequality", "fixed size", "probability", "measure assigning equal probabilities" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2011arXiv1105.3862V" } } }