It is known that the Decision Diffie-Hellman (DDH) problem can be easily solved over groups on pairing friendly curves (that is: one can use pairing to tell if $g^x$ and $g^y$ and $g^z$ forms a DH tuple such that $z = x*y$). What about the "tripartite" case where one has the tuple ($g^x$, $g^y$, $g^z$ and $g^u$) and need to tell if $u= x*y*z$. Would that be easy?
It looks like not an easy problem to me, as pairing can only be applied once?
