fixed #235

chapters/information-structure.tex

@@ -267,7 +267,7 @@ \section{Information structure in the architecture of signs}
 use \textit{diff-list}\istype{diff-list}\is{list!difference} as values for the features \textsc{rels}, \textsc{hcons}
 and \textsc{icons} (expressed by the ``!'' at the beginning and the
 end of the list). This type of list includes an explicit pointer
-to the last element of the list, which is usefull for appending\isrel{append} lists in variants of
+to the last element of the list, which is useful for appending\isrel{append} lists in variants of
 the theory that do not use relational constraints\is{relational constraint} like \texttt{append} that is used elsewhere in this book. See \citew[Section~4.3]{Copestake2002a} for details.
 \ea\label{fig:song-infostruc}
 Information structure in \citew{song-bender:2012} and \citew[116]{song2018}:\\