Fixed spelling error and removed duplicate Weak Entity section

130.tex

@@ -164,23 +164,16 @@ \subsubsection{Entity Sets and attributes}
 
 \begin{enumerate}
 \item \emph{Composite attributes}: flatten to contain only simple attributes.
-\item \emph{Multivalued attributes}: own relation mappped back to entity
+\item \emph{Multivalued attributes}: own relation mapped back to entity
 set using foreign key.
 \item \emph{Derived attributes}: not supported by relational model.
 \end{enumerate}
 
 \paragraph{Weak Entity Sets}
 
-Mapped to its own realtion and attributes but includes primary key
+Mapped to its own relation and attributes but includes primary key
 of strong attribute with on delete cascade constraint.
 
-
-\subsubsection{Weak Entity Sets}
-
-Mapped to its own realtion and attributes but includes primary key
-of strong attribute with on delete cascade constraint.
-
-
 \subsubsection{Relationships}
 
 \emph{Many-to-many}: new relation with two foreign keys. E.g.