${\mbox{$| \psi \rangle$}}$ and ${\mbox{$| \phi \rangle$}}$ are typically not related by LU, and continuous parameters are needed to label all equivalence classes [@Li97; @Sc; @Su00; @Ca00; @Ke99]. That is, one has to deal with infinitely many kinds of entanglement. In this context an alternative, simpler classification would be advisable.

One such classification is possible if we just demand that the conversion of the states is through stochastic local operations and classical communication (SLOCC) [@Be99]; that is, through LOCC but without imposing that it has to be achieved with certainty. In that case we can establish an equivalence relation stating that two states ${\mbox{$| \psi \rangle$}}$ and ${\mbox{$| \phi \rangle$}}$ are equivalent if the parties have a non-vanishing probability of success when trying to convert ${\mbox{$| \psi \rangle$}}$ into ${\mbox{$| \phi \rangle$}}$, and also ${\mbox{$| \phi \rangle$}}$ into ${\mbox{$| \psi \rangle$}}$ [@comment]. This relation has been termed stochastic equivalence in Ref.  [@Be99]. Their equivalence under SLOCC indicates that both states are again suited to implement the same tasks of QIT, although this time the probability of a successful performance of the task may differ from ${\mbox{$| \phi \rangle$}}$ to ${\mbox{$| \psi \rangle$}}$. Notice in addition that since LU are a 