  Alon, Shpilka and Umans considered the following version of usual
sunflower-free subset: a subset $\mbox{$\cal F$}\subseteq \{1,\ldots ,D\}^n$
for $D>2$ is sunflower-free if for every distinct triple $x,y,z\in \mbox{$\cal
F$}$ there exists a coordinate $i$ where exactly two of $x_i,y_i,z_i$ are
equal. Combining the polynomial method with character theory Naslund and Sawin
proved that any sunflower-free set $\mbox{$\cal F$}\subseteq \{1,\ldots ,D\}^n$
has size $$ |\mbox{$\cal F$}|\leq c_D^n, $$ where
$c_D=\frac{3}{2^{2/3}}(D-1)^{2/3}$.
  In this short note we give a new upper bound for the size of sunflower-free
subsets of $\{1,\ldots ,D\}^n$.
  Our main result is a new upper bound for the size of sunflower-free
$k$-uniform subsets.
  More precisely, let $k$ be an arbitrary integer. Let $\mbox{$\cal F$}$ be a
sunflower-free $k$-uniform set system. Consider $M:=|\bigcup\limits_{F\in
\mbox{$\cal F$}} F|. $ Then $$ |\mbox{$\cal F$}|\leq
3(\lceil\frac{2k}{3}\rceil+1)(2^{1/3}\cdot 3e)^k(\lceil\frac Mk\rceil
-1)^{\lceil\frac{2k}{3}\rceil}. $$
  In the proof we use Naslund and Sawin's result about sunflower-free subsets
in $\{1,\ldots ,D\}^n$.
