a4/question2.tex

   1 In order to be allow learnlib to learn the TCP model it was necessary to have a
   2 deterministic model.  We accomplished this by modifying the adapter so it can
   3 reach a \texttt{ERROR} or \texttt{CLOSED} state. In these states all inputs are
   4 discarded and a default output is returned.  In the case of a state where an
   5 input results in a non-deterministic output we jump to the \texttt{ERROR} which will give the \emph{ERR} output for any input.
   6 When the connection is successfully closed
   7 using a \texttt{FIN} packet we move the adapter to the \texttt{CLOSED} state.
   8
   9 We divided the input alphabet into three sets, this way we can control the size
  10 of the model learned by learnlib.
  11
  12 \begin{table}[H]
  13         \begin{tabular}{cl}
  14                 \toprule
  15                 Alphabet & Inputs \\
  16                 \midrule
  17                 small & \texttt{SYN}, \texttt{ACK} \\
  18                 partial & \texttt{SYN}, \texttt{ACK}, \texttt{DATA} \\
  19                 full & \texttt{SYN}, \texttt{ACK}, \texttt{DATA}, \texttt{RST},
  20                         \texttt{FIN} \\
  21                 \bottomrule
  22         \end{tabular}
  23         \caption{Different input alphabets used during learning.}
  24 \end{table}
  25
  26 Just as in our previous assignment the \texttt{DATA} packet is actually a
  27 \texttt{ACK} with an user data payload and the \emph{push} flag set.  These
  28 input alphabets will influence the size of the model produced. \emph{small}
  29 will result in a 2 state model, \emph{partial} will be the full model without
  30 the \texttt{CLOSED} state and \emph{full} should result in the full model as
  31 used in the previous assignment.
  32
  33 \begin{figure}[H]
  34         \centering
  35         \includegraphics[scale=0.75]{model.small.LStar.rand.eps}
  36         \vspace{5mm}
  37         \caption{Model learned with small input alphabet}
  38 \end{figure}
  39
  40 \begin{figure}[H]
  41         \centering
  42         \includegraphics[width=\textwidth]{model.partial.LStar.rand.eps}
  43         \vspace{5mm}
  44         \caption{Model learned with partial input alphabet}
  45 \end{figure}
  46
  47 \begin{figure}[H]
  48         \centering
  49         \includegraphics[width=1.2\textwidth]{model.full.LStar.rand.eps}
  50         \vspace{5mm}
  51         \caption{Model learned with full input alphabet}
  52 \end{figure}