比利时vs摩洛哥足彩
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university of california san diego
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graduate student combinatorics seminar
sam spiro
ucsd
the r$\ddot{\text{o}}$dl nibble
abstract:
an $(n,k,\ell)$-design is a a family of $k$-sets of $[n]$ such that every $\ell$-set is covered precisely once. the problem of determining whether or not there exists a design for a given set of parameters is a classical and difficult question in combinatorics. we ask a variant of this problem. namely, given $k,\ell$, can one find a family of $k$-sets of $[n]$ covering every $\ell$-set \textit{at least} once that has ``approximately'' as many sets as an $(n,k,\ell)$-design would have? in this talk we will solve the above problem using the technique known as the r$\ddot{\text{o}}$ dl nibble. as time permits we will also discuss other problems in design theory, as well as other applications of the r$\ddot{\text{o}}$dl nibble technique.
march 1, 2019
9:00 am
ap&m 5402
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