  For every graph $G$, let $\omega(G)$ be the largest size of complete subgraph
in $G$. This paper presents a simple algorithm which, on input a graph $G$, a
positive integer $k$ and a small constant $\epsilon>0$, outputs a graph $G'$
and an integer $k'$ in $2^{\Theta(k^5)}\cdot |G|^{O(1)}$-time such that (1)
$k'\le 2^{\Theta(k^5)}$, (2) if $\omega(G)\ge k$, then $\omega(G')\ge k'$, (3)
if $\omega(G)<k$, then $\omega(G')< (1-\epsilon)k'$. This implies that no
$f(k)\cdot |G|^{O(1)}$-time algorithm can distinguish between the cases
$\omega(G)\ge k$ and $\omega(G)<k/c$ for any constant $c\ge 1$ and computable
function $f$, unless $FPT= W[1]$.
