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SUMMARY:Questions on Symmetric Chains (Shahriar Shahriari\, Pomona)
DESCRIPTION:The set of subsets {1\, 3}\, {1\, 3\, 4}\, {1\, 3\, 4\, 6} is a symmetric chain in the partially ordered set (poset) of subsets of {1\,…\,6}. It is a chain\, because each of the subsets is a subset of the next one. It is symmetric because the collection has as many subsets with less than 3 elements as it has subsets with more than 3 elements (3 is half of 6\, the size of the original set). It is straightforward to partition the set of all subsets of {1\,…\,6} into symmetric chains. Such a partition is called a symmetric chain decomposition of the poset. We are interested in the following—admittedly curious sounding—question. What is the maximum integer k\, such that given any collection of k disjoint symmetric chains in the poset of subsets of a finite set\, we can enlarge the collection to a symmetric chain decomposition of the poset? I don’t know the answer\, but in this talk\, I will discuss a special case\, a number of related results and questions\, and provide some background on why symmetric chain decompositions are useful.
URL:https://colleges.claremont.edu/ccms/event/antc-seminar-shahriar-shahriari-pomona/
LOCATION:On Zoom
CATEGORIES:Algebra / Number Theory / Combinatorics Seminar
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