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比利时vs摩洛哥足彩 ,
university of california san diego

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math 269 - combinatorics

boris bukh

princeton university

stabbing simplices by points and affine spaces

abstract:

b\'ar\'any showed that there is a constant $c_d>0$ such that if $s$ is any $n$-point set in $r^d$, then there exists a point in $c_d$ fraction of simplices spanned by $s$. we present a simple construction of a point set for which there is no point contained in many simplices. the construction is optimal for $d=2$ and gives the first non-trivial upper bounds on $c_d$ for $d\geq 3$. we will also discuss generalizations to stabbing simplices by affine spaces. joint work with ji\v{r}\'\i{} matou\v{s}ek and gabriel nivasch.

host: jacques verstraete

march 25, 2008

4:00 pm

ap&m 7321

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