A draft research paper claims that $Q(p)=1-p_1 p_2 p_3 p_4 - p_2 p_3 p_6 p_7-p_1p_2$ is multilinear where $p_i = \mathbb P(e_i)$ and $e_i$ is a basic event of a component to fail.
I have learnt in LP course that even a function $Q_2(p)=p_1 p_2$ is quadratic when $p_1,p_2 \in \{0,1\}$, not LP. I find the part "linear" confusing in the word "multilinear". The claim is so that $Q(p)$ is a multilinear function. What does this "multilinear" mean? Is this quadratic constraint $Q_2(p)$ multilinear?