Remove stray repetition of part of sentence

chapters/functions.tex

@@ -1567,7 +1567,6 @@ \section{Declaring Inverses of Functions}\label{declaring-inverses-of-functions}
 
 The function in the \lstinline!inverse! annotation must be an actual inverse.
 This requires that $f_2$ is such that, if $u_k$ is calculated as \lstinline!$u_k$ := $f_2$($\ldots$, y, $\ldots$)!, the equality \lstinline!y = $f_1$($\ldots$, $u_k$, $\ldots$)! is satisfied up to a certain precision, for all valid values of the input arguments of \lstinline!$f_2$($\ldots$, y, $\ldots$)!.
-the equality \lstinline!y = $f_1$($\ldots$, $u_k$, $\ldots$)! is satisfied up to a certain precision.
 
 Function $f_1$ can have any number and types of formal parameters with and without default value.
 The restriction is that the \emph{number of unknown variables} (see \cref{balanced-models}) in the output formal parameter of both $f_1$ and $f_2$ must be the same and that $f_2$ should have a union of output and formal parameters that is the same or a sub-set of that union for $f_1$, but the order of the formal parameters may be permuted.