  A general hypergeometric construction of linear forms in (odd) zeta values is
presented. The construction allows to recover the records of Rhin and Viola for
the irrationality measures of $\zeta(2)$ and $\zeta(3)$, as well as to explain
Rivoal's "infinitely-many" result (math.NT/0008051) and to prove that at least
one of the four numbers $\zeta(5)$, $\zeta(7)$, $\zeta(9)$, and $\zeta(11)$ is
irrational.
