You can use arrow keys to navigate in the map.
This would lead to unuseful usage of the chat, not necessarily allowing ones to discuss seriously.
Discussing arguments outside of the tree would cause users to develop a bias before they submit a premise based on their own beliefs.
If the premise is not clear, then it becomes impossible to respond to it.
In that case the respondent has to assume all possible meanings, and then respond in "if... then..." manner.
It is better to have a request the sender to clarify his position.
The core benefit of an argumentation graph is that it avoids personal comments and focuses on the logic. If a parallel chat is allowed, this will be nullified.
People are apt to carry on arguing in the chat section as well. These premises would be hidden in the chat, and although they are explicitly placed on record, they would not have any effect on the outcome of the debate.
if someone does not get what someone else meant he can ask him in the chat and dose not have to do a lot of howevers to ask untill he gets it