On the top of page 4 of this paper Direct Construction of Minimal Acyclic Subsequential Transducers, there is an expression
$$\forall r \in S\ \forall a \in \Sigma\ \forall \sigma \in \Sigma^*\ ((\mu^*(s,\sigma)=r\ \& \ !\mu(r,a)) \to \lambda(r,a)=[g\mathcal T(\sigma) ]^{-1}g\mathcal T(\sigma a))$$
What's the meaning of the ampersand and the exclamation mark? I guess that $\&$ means "and", but shouldn't it be $\land$?
Thanks.