Research on non-task-oriented dialogue systems like casual conversation dialogue systems ("chatbots") is on the other hand not very common, perhaps due to the many amateurs who try to build naturally talking systems using sometimes very clever, but rather unscientific methods although there are systems with chatting abilities as (Bickmore and Cassell, 2001) but concentrate on applying strategies to casual conversation rather than their automatic generation of those conversations.
we believe that the main reason is that an unrestricted domain is disproportionately difficult compared to the possible use such a system could have.