"main discussion" is a correct and usable phrase in written English.
You can use it when introducing a topic or summarizing a conversation. For example, "In this meeting, the main discussion was about our upcoming product launch."
A numerical example illustrates the main discussion of this article.
The main discussion is of the "war on terror" and Afghanistan.
The two couples were pointedly drinking and smoking... Their main discussion point was doughnuts.
At some point Lord's defenses — rather than his initial remarks — became the main discussion topic.
But the main discussion of carbon budgets will have to wait for the next instalments of the report next year.
The Net-Admin-L list is the main discussion forum for anyone maintaining a network, or networked computers, at Cornell.
The main discussion has been about moving away from analyses of variance (ANOVAs) to linear mixed effects models.
The note, written in blue ink with a spidery hand, listed the main discussion topics, from voting reform to party funding and fixed-term parliaments.
At this point it is necessary to emphasize that the main discussion is given to Czech large size manufacturing companies from both points of view.
Our main discussion was not that faith-based charities need money but that we need freedom: the removal of current obstacles, including government regulations, that hinder us in the effort to provide social services.
This week, she is to make her pitch to European Union leaders at a summit meeting in Brussels, but the main discussion of Britain's departure from the bloc will happen after Mrs. May has left the room.
