privacy: Reviewed subsec:prv-levels

text/preliminaries/privacy.tex

@@ -51,8 +51,11 @@ In order to better protect the privacy of Donald in case of attacks, the data sh
 \subsection{Levels of privacy protection}
 \label{subsec:prv-levels}
 
-The information disclosure that a data release may entail is linked to the protection level that indicates \emph{what} a privacy-preserving algorithm is trying to achieve.\kat{I don't understand this first sentence}
-More specifically, in continuous data publishing we consider the privacy protection level with respect to not only the users, but also to the \emph{events} occurring in the data.
+% The information disclosure that a data release may entail is linked to the protection level that indicates \emph{what} a privacy-preserving algorithm is trying to achieve.
+% \kat{I don't understand this first sentence}
+% \mk{Same here...}
+% More specifically, i
+In continuous data publishing we consider the privacy protection level with respect to not only the users, but also to the \emph{events} occurring in the data.
 An event is a pair of an identifying attribute of an individual and the sensitive data (including contextual information) and we can see it as a correspondence to a record in a database, where each individual may participate once.
 Data publishers typically release events in the form of sequences of data items, usually indexed in time order (time series) and geotagged, e.g.,~(`Dewey', `at home at Montmartre at $t_1$'), \dots, (`Quackmore', `dining at Opera at $t_1$').
 We use the term `users' to refer to the \emph{individuals}, also known as \emph{participants}, who are the source of the processed and published data.
@@ -61,9 +64,13 @@ Users are subject to privacy attacks, and thus are the main point of interest of
 In more detail, the privacy protection levels are:
 
 \begin{enumerate}[(a)]
-  \item \emph{Event}~\cite{dwork2010differential, dwork2010pan}---limits the privacy protection to \emph{any single event} in a time series, providing maximum \kat{maximum? better say high} data utility.
+  \item \emph{Event}~\cite{dwork2010differential, dwork2010pan}---limits the privacy protection to \emph{any single event} in a time series, providing high
+  % \kat{maximum? better say high}
+  data utility.
   \item \emph{$w$-event}~\cite{kellaris2014differentially}---provides privacy protection to \emph{any sequence of $w$ events} in a time series.
-  \item \emph{User}~\cite{dwork2010differential, dwork2010pan}---protects \emph{all the events} in a time series, providing maximum\kat{maximum? better say high}  privacy protection.
+  \item \emph{User}~\cite{dwork2010differential, dwork2010pan}---protects \emph{all the events} in a time series, providing high
+  % \kat{maximum? better say high}
+  privacy protection.
 \end{enumerate}
 
 Figure~\ref{fig:prv-levels} demonstrates the application of the possible protection levels on the statistical data of Example~\ref{ex:continuous}.
@@ -71,6 +78,7 @@ For instance, in event-level (Figure~\ref{fig:level-event}) it is hard to determ
 Moreover, in user-level (Figure~\ref{fig:level-user}) it is hard to determine whether Quackmore was ever included in the released series of events at all.
 Finally, in $2$-event-level (Figure~\ref{fig:level-w-event}) it is hard to determine whether Quackmore was ever included in the released series of events between the timestamps $t_1$ and $t_2$, $t_2$ and $t_3$, etc. (i.e.,~for a window $w = 2$).
 \kat{Already, by looking at the original counts, for the reader it is hard to see if Quackmore was in the event/database. So, we don't really get the difference among the different levels here.}
+\mk{It is without background knowledge.}
 
 \begin{figure}[htp]
   \centering
@@ -83,7 +91,10 @@ Finally, in $2$-event-level (Figure~\ref{fig:level-w-event}) it is hard to deter
   \subcaptionbox{$2$-event-level\label{fig:level-w-event}}{%
     \includegraphics[width=.32\linewidth]{level-w-event}%
   }\hspace{\fill}
-  \caption{Protecting the data of Table~\ref{tab:continuous-statistical} on (a)~event-, (b)~user-, and (c)~$2$-event-level. A suitable distortion method can be applied accordingly. \kat{Why don't you distort the results already in this table?}}
+  \caption{Protecting the data of Table~\ref{tab:continuous-statistical} on (a)~event-, (b)~user-, and (c)~$2$-event-level. A suitable distortion method can be applied accordingly. 
+  % \kat{Why don't you distort the results already in this table?}
+  % \mk{Because we've not discussed yet about these operations.}
+  }
   \label{fig:prv-levels}
 \end{figure}