Hi,
It is very important to set a minimum number of posting in online dicussions. The quality of posting is very important as well. Oneliner posting should not be credited with any points. I think, a minimum of three postings per topic is a logical standard for any online discussions. The first posting should be the introduction, second one should be response to someone else's posting and extend thoughts, and the final posting should be a summarized thoughts on the topic.
