diff --git a/docs/rtfm/intro 80 char b/docs/rtfm/intro 80 char
index 081f18d..3c7d32a 100644
--- a/docs/rtfm/intro 80 char	
+++ b/docs/rtfm/intro 80 char	
@@ -141,3 +141,23 @@ How can gem-graph be used to analyse and control the complexity of what it
 represents and sets in motion? This chapter introduces the gem-graph mechanism.
 
 
+------------
+
+Gem-graph can reproduce the behavior of any cellular automata. Whatever the state
+of the cellular automaton space at a given time (n), this state can be considered
+as a gem-graph state and a rule can be written to transform it into the next
+state (n+1).
+
+The difference with the cellular automaton is that this rule is not generated by
+a "micro-rule" applied cell by cell to the entire state (n). This rule must be
+written by hand and its writing requires knowledge of state (n+1).
+
+Writing all the rules that describe all the transformations that have occurred
+when a cellular automaton describes a trajectory (a story) is certainly tedious,
+but it is always possible. And the number of possible histories that gem-graph
+rules can describe is limited only by the size of the space and the number of
+symbols it contains.
+
+If a set of "micro-rules", each applied cell by cell to the entire state (n) of
+a cellular automaton, can produce all the possible states that the gem-graph can
+describe, the two representations can be considered to be equivalent in power.