report: review stats query

doc/report/applications.tex

 \section{Applications}\label{sec:applications}
 
-With endpoints in place, we can now query the ULO/RDF data set. This
-section describes some experiments with the \emph{ulo-endpoint}
-Endpoint {API}. In particular, we query the storage backend for some
-statistics, implement some queries suggested for tetrapodal search
-
-\subsection{Exploring Existing Data Sets}
-
-As previously stated, there already exist exports to ULO for both
-Isabelle and Coq libraries~\cite{uloisabelle, ulocoq}. As a very first
-application, we simply look at what ULO predicates are actually used
-by the respective data sets.  Implementing such a query is not very
-difficult.  In SPARQL, this can be achieved with the \texttt{COUNT}
-aggregate.
+With programming endpoints in place, we can now query the data set containing
+both Isabelle and Coq exports stored in {GraphDB}. We experimented with
+various queries and applications:
+
+\begin{itemize}
+    \item Exploring which ULO predicates are actually used and which
+      remain unused (Section~\ref{sec:expl}).
+
+    \item We ran some queries that were suggested as building blocks
+      of a larger tetrapodal search system (Section~\ref{sec:tetraq}).
+
+    \item We also experimented with various other more general queries
+      for organizational data recommended in literature
+      (Section~\ref{sec:miscq}).
+
+    \item Finally we built a small web front end that takes visualizes
+      the ULO data set (Section~\ref{sec:webq}).
+\end{itemize}
+
+For each example query or application, we try to describe how to
+implement it, what results we observed and if possible we conclude
+with some recommendations for future development of {ULO}.
+
+\subsection{Exploring Existing Data Sets}\label{sec:expl}
+
+As a very first application, we simply looked at what ULO predicates
+are actually used by the respective data sets. With more than
+250~million triplets in the store, we hoped that this would give us
+some insight into the kind of knowledge we are dealing with.
+
+Implementing a query for this job is not very difficult. In SPARQL,
+this can be achieved with the \texttt{COUNT} aggregate.
 \begin{lstlisting}
     PREFIX ulo: <https://mathhub.info/ulo#>
 
@@ -27,7 +46,7 @@ This yields a list of all used predicates with \texttt{?count} being
 the number of occurrences. Looking at the results, we find that both
 the Isabelle and the Coq data sets only use subsets of the predicates
 provided by the ULO ontology. The results are listed in
-figure~\ref{fig:used}. In both cases, the exports use less than a
+Figure~\ref{fig:used}. In both cases, the exports use less than a
 third of the available predicates.
 
 \input{applications-ulo-table.tex}
@@ -37,19 +56,23 @@ predicates.  For example, the Isabelle contains organizational meta
 information such as information about paragraphs and sections in the
 source document while the Coq export only tells us about the filename
 of the Coq source. That is not particularly problematic as long as we
-can trace a given object back to the original Isabelle/Coq source.
-
-However, our results do show that both exports have their own
-particularities and with more and more third party libraries exported
-to ULO one can assume that this heterogeneity only grows. In particular
-we want to point to the large number of predicates which remain unused
-in both Isabelle and Coq exports. A user formulating queries for ULO
-might be oblivious to the fact that only subsets of exports support
-given predicates. While not a problem for \emph{ulo-storage} per se,
-we expect this to be a major challenge when building a system of
-tetrapodal search.
-
-\subsection{Querying for Tetrapodal Search}
+can trace a given object back to the original source.  Regardless, our
+results do show that both exports have their own particularities and
+with more and more third party libraries exported to ULO one has to
+assume that this heterogeneity will only grow. In particular we want
+to point to the large number of predicates which remain unused in both
+Isabelle and Coq exports. A user formulating queries for ULO might be
+oblivious to the fact that only subsets of exports support given
+predicates.
+
+While not a problem for \emph{ulo-storage} per se, we do expect this
+to be a challenge when building a tetrapodal search
+system. Recommended ways around this ``missing fields'' problem in
+database literature include the clever use of default values or
+inference of missing values~\cite{kdisc, aidisc}, neither of which
+feels particularly applicable to an ULO data set.
+
+\subsection{Querying for Tetrapodal Search}\label{sec:tetraq}
 
 \emph{ulo-storage} was started with the goal of making organizational
 knowledge available for tetrapodal search. We will first take a look
@@ -259,6 +282,8 @@ proof of concept implementations.
     handled by the database access should be quick.
 \end{itemize}
 
-\subsection{Other Queries}
+\subsection{Organizational Queries}\label{sec:miscq}
 
 \emph{{TODO}: SPARQL Queries references in ULO paper}
+
+\subsection{Experience with Building a Web Frontend}\label{sec:webq}

doc/report/references.bib

@@ -154,3 +154,20 @@
     year={2013},
     publisher={" O'Reilly Media, Inc."}
 }
+
+@article{kdisc,
+  title={Knowledge discovery in databases: An overview},
+  author={Frawley, William J and Piatetsky-Shapiro, Gregory and Matheus, Christopher J},
+  journal={AI magazine},
+  volume={13},
+  number={3},
+  pages={57--57},
+  year={1992}
+}
+
+@inproceedings{aidisc,
+  title={Discovering Missing Values in Semi-Structured Databases.},
+  author={Yi, Xing and Allan, James and Lavrenko, Victor},
+  booktitle={RIAO},
+  year={2007}
+}