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diff --git a/methods.top.tex b/methods.top.tex
index 982ac24..ec330c9 100644
--- a/methods.top.tex
+++ b/methods.top.tex
@@ -1,10 +1,9 @@
-\section{\acrlong{TOP}}
-\subsection{\gls{iTasks}}
-\gls{TOP} is a recent programming paradigm implemented as
+\section{iTasks}
+\gls{TOP} is a modern recent programming paradigm implemented as
 \gls{iTasks}\cite{achten_introduction_2015} in the pure lazy functional
 language \gls{Clean}\cite{brus_cleanlanguage_1987}. \gls{iTasks} is a
-\gls{EDSL} to model workflow tasks in the broadest sense. A \CI{Task} is just
-a function that, given some state, returns the observable \CI{TaskValue}. The
+\gls{EDSL} to model workflow tasks in the broadest sense. A \gls{Task} is just
+a function that --- given some state --- returns the observable \CI{TaskValue}. The
 \CI{TaskValue} of a \CI{Task} can have different states. Not all state
 transitions are possible as shown in Figure~\ref{fig:taskvalue}. Once a value
 is stable it can never become unstable again. Stability is often reached
@@ -16,9 +15,11 @@ A simple \gls{iTasks} example illustrating the route to stability of a
 Listing~\ref{lst:taskex}. The code is accompanied by screenshots showing the
 user interface in Figure~\ref{fig:taskex1},~\ref{fig:taskex2}
 and~\ref{fig:taskex3}. The \CI{TaskValue} of the \gls{Task} is in the first
-image in the \CI{NoValue} state, the second and third image have an
+image in the \CI{NoValue} state, the second image does not have all the fields
+filled in and therefore the \CI{TaskValue} remains \CI{Unstable}. In the third
+image all fields are entered and the \CI{TaskValue} transitions to the
 \CI{Unstable} state. When the user presses \emph{Continue} the value becomes
-\CI{Stable}.
+\CI{Stable} and cannot be changed any further.
 
 \begin{figure}[H]
 	\centering
@@ -26,7 +27,7 @@ image in the \CI{NoValue} state, the second and third image have an
 	\caption{The states of a \CI{TaskValue}}\label{fig:taskvalue}
 \end{figure}
 
-\begin{lstlisting}[language=Clean,label={lst:taskex},%
+\begin{lstlisting}[label={lst:taskex},%
 	caption={An example \gls{Task} for entering a name}]
 :: Name = { firstname :: String
           , lastname  :: String
@@ -41,6 +42,7 @@ enterName = enterInformation "Enter your name" []
 \end{lstlisting}
 
 \begin{figure}[H]
+	\centering
 	\begin{subfigure}{.25\textwidth}
 		\centering
 		\includegraphics[width=.9\linewidth]{taskex1}
@@ -59,10 +61,127 @@ enterName = enterInformation "Enter your name" []
 	\caption{Example of a generated user interface}
 \end{figure}
 
-For a type to be suitable it must have instances for a collection of generic
-functions that are captured in the class \CI{iTask}. Basic types have
+For a type to be suitable, it must have instances for a collection of generic
+functions that is captured in the class \CI{iTask}. Basic types have
 specialization instances for these functions and show an according interface.
 Generated interfaces can be modified with decoration operators.
 
-\subsection{Combinators}
-\todo{Stukje over combinators, in ieder geval bind en paralel}
+\section{Combinators}
+\Glspl{Task} can be combined using so called \gls{Task}-combinators.
+Combinators describe relations between \glspl{Task}. \Glspl{Task} can be
+combined in parallel, sequenced and their result values can be converted to
+\glspl{SDS}. Moreover, a very important combinator is the step combinator which
+starts a new task according to specified predicates on the \CI{TaskValue}.
+Type signatures of the basic combinators are shown in
+Listing~\ref{lst:combinators}.
+
+\begin{itemize}
+	\item Step:
+
+		The step combinator is used to start \glspl{Task} when a predicate on
+		the \CI{TaskValue} holds or an action has taken place. The bind
+		operator can be written as a step combinator.
+		\begin{lstlisting}[language=Clean]
+(>>=) infixl 1 :: (Task a) (a -> (Task b)) -> (Task b) | iTask a & iTask b
+(>>=) ta f = ta >>* [OnAction "Continue" onValue, OnValue onStable]
+    where
+        onValue (Value a _)     = Just (f a)
+        onValue _               = Nothing
+
+        onStable (Value a True) = Just (f a)
+        onStable _              = Nothing
+		\end{lstlisting}
+	\item Parallel:
+
+		The parallel combinator allows for concurrent \glspl{Task}. The
+		\glspl{Task} combined with these operators will appear at the same time
+		in the web browser of the user and the results are combined as the type
+		dictates.
+\end{itemize}
+
+\begin{lstlisting}[%
+	caption={\Gls{Task}-combinators},label={lst:combinators}]
+//Step combinator
+(>>*)  infixl 1 :: (Task a) [TaskCont a (Task b)] -> Task b     | iTask a & iTask b
+(>>=)  infixl 1 :: (Task a) (a -> Task b)         -> Task b   | iTask a & iTask b
+:: TaskCont a b
+	=     OnValue             ((TaskValue a)  -> Maybe b)
+	|     OnAction    Action  ((TaskValue a)  -> Maybe b)
+	| E.e: OnException         (e              -> b)       & iTask e
+	|     OnAllExceptions     (String         -> b)
+:: Action = Action String
+
+//Parallel combinators
+(-||-) infixr 3 :: (Task a) (Task a)              -> Task a     | iTask a
+(||-)  infixr 3 :: (Task a) (Task b)              -> Task b     | iTask a & iTask b
+(-||)  infixl 3 :: (Task a) (Task b)              -> Task a     | iTask a & iTask b
+(-&&-) infixr 4 :: (Task a) (Task b)              -> Task (a,b) | iTask a & iTask b
+\end{lstlisting}
+
+\section{Shared Data Sources}
+\Glspl{SDS} are an abstraction over resources that are available in the world
+or in the \gls{iTasks} system. The shared data can be a file on disk, the
+system time, a random integer or just some data stored in memory. The actual
+\gls{SDS} is just a record containing functions on how to read and write the
+source. In these functions the \CI{*IWorld} --- which in turn contains the real
+program \CI{*World} --- is available. Accessing the outside world is required
+for interacting with it and thus the functions can access files on disk, raw
+memory, other shares and hardware.
+
+The basic operations for \glspl{SDS} are get, set and update. The signatures
+for these functions are shown in Listing~\ref{lst:shares}. By default, all
+shares are files containing a \gls{JSON} encoded version of the object and thus
+are persistent between restarts of the program. Library functions for shares
+residing in memory are available as well. The three main operations on shares
+are atomic in the sense that during reading no other tasks are executed. The
+system provides useful functions to transform, map and combine \glspl{SDS}
+using combinators. The system also provides functionality to inspect the value
+of a \gls{SDS} and act upon a change. \Glspl{Task} waiting on a \gls{SDS} to
+change are notified when needed. This results in low resource usage because
+\glspl{Task} are never constantly inspecting \gls{SDS} values but are notified.
+
+\begin{lstlisting}[%
+	label={lst:shares},caption={\Gls{SDS} functions}]
+:: RWShared p r w = ... 
+:: ReadWriteShared r w :== RWShared () r w
+:: ROShared p r :== RWShared p () r
+:: ReadOnlyShared r :== ROShared () r
+
+:: Shared r :== ReadWriteShared r r
+
+get ::          (ReadWriteShared r w)           -> Task r | iTask r
+set :: w        (ReadWriteShared r w)           -> Task w | iTask w
+upd :: (r -> w) (ReadWriteShared r w)           -> Task w | iTask r & iTask w
+
+sharedStore :: String a -> Shared a | JSONEncode{|*|}, JSONDecode{|*|}
+\end{lstlisting}
+
+\section{Parametric Lenses}
+\Glspl{SDS} can contain complex data structures such as lists, trees and even
+resources in the outside world. Sometimes, an update action only updates a part
+of the resource. When this happens, all waiting \glspl{Task} looking at the
+resource are notified of the update. However, it may be the case that
+\glspl{Task} where only looking at parts of the structure that was not updated.
+To solve this problem, parametric lenses were
+introduced~\cite{domoszlai_parametric_2014}.
+
+Parametric lenses add a type variable to the \gls{SDS} that is in the current
+library functions fixed to \CI{()}. When a \gls{SDS} executes a write
+operation it also provides the system with a notification predicate. This
+notification predicate is a function \CI{p -> Bool} where \CI{p} is the
+parametric lens type. This allows programmers to create a big share, and have
+\glspl{Task} only look at parts of the big share. This technique is used in the
+current system in memory shares. The \CI{IWorld} contains a map that is
+accessible through an \gls{SDS}. While all data is stored in the map, only
+\glspl{Task} looking at a specific entry are notified when the structure is
+updated. The type of the parametric lens is the key in the map.
+
+Functionality for setting parameters is added in the system. The most important
+function is the \CI{sdsFocus} function. This function is listed in
+Listing~\ref{lst:focus} and allows the programmer to fix the parametric lens to
+a value.
+
+\begin{lstlisting}[label={lst:focus},
+	caption={Parametric lens functions}]
+sdsFocus :: p (RWShared p r w) -> RWShared p` r w | iTask p
+\end{lstlisting}