diff --git a/opensym2017/content/04-architecture.tex b/opensym2017/content/04-architecture.tex
index 62106d7..ff74bfc 100644
--- a/opensym2017/content/04-architecture.tex
+++ b/opensym2017/content/04-architecture.tex
@@ -48,45 +48,24 @@ the change between applications. For that, Colab provides facilities
 for:
 
 \begin{itemize}
-  \item Centralized authentication
-  \item Visual consistency
-  \item Relaying of events between applications
-  \item Integrated search engine
+  \item \textit{Centralized authentication}: Users are automatically 
+identified for each application without having to enter login
+credentials on each of them.
+  \item \textit{Visual consistency}: Colab is able to change the HTML
+code produced by the integrated applications, such as defining default
+template or reusing common HTML pages, in order to provide a unified
+interface.
+  \item \textit{Relaying of events between applications}: The
+integrated applications or Colab itself are able to trigger an action
+on another application.
+  \item \textit{Integrated search engine}: It is possible to set up
+exactly which data needs to be indexed from each application and how
+users are directed to this information on correspondent application.
 \end{itemize}
 
 Colab implements this integration by working as a reverse proxy for the
 integration applications, that is, all external requests pass through
-Colab before reaching them.
-
-Centralized authentication is handled by letting users authenticate to
-Colab, which then sends a REMOTE\_USER HTTP header to applications,
-which are expected to be pre-configured to accept that as an indication
-of the current user (REMOTE\_USER is a standard authentication mechanism
-for web applications). This allows users to be automatically identified
-to each of the applications without having to enter credentials for each
-of them.
-%
-Of course, this requires that the integrated applications are not
-accessible on the public internet, otherwise malicious users could send
-their own crafted REMOTE\_USER headers and impersonate any user.
-
-For the visual consistency, Colab is able to make transformations to the
-HTML produced by the integrated applications, ir order to provide a
-unified interface. It allows one to define default templates to be used
-by all applications, as well as providing extra ones in a plugin. This
-approach allowed us to reuse common HTML pages, what facilitates
-maintenance.
-
-Colab also provides a publish-subscribe event system. This allows one of
-the applications, or Colab itself, to trigger an action in another
-application. For example, when a user registers with Colab, all
-applications need to be notified in order to create their own internal
-representation of that user account.
-
-Colab also provides an integrated search engine, which can be configured
-to specify exactly what data needs to be indexed for each of the
-applications, and how to direct the user to that piece of information on
-the specific application.
+Colab before reaching them. 
 
 Initially, Colab had support for a small set of applications (Trac, GNU
 Mailman, and Apache Lucene) and support for them was hard-coded. Our
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