I do not think you are aware of the fact that a PLA infantry division is much smaller than an Indian or Pakistani Infantry division. Most PLA mountain divisions have been downsized to consist of only two regiments. Thus the pre-reduction number of 12000 to 13000 troops have been reduced to 8000 to 10,000 in most divisions. An IA mountain division in contrast has 15,000 combat troops.
For offensive ops in mountainous terrain an attacker needs a combat ration of 9:1 ie, nine times the defensive force it is attacking. So four IA mountain divisions are sufficient to thwart any offensive by the PLA considering that it can bring to bear a total of only 30 mountain divisions including reserves in the theater of ops we are talking about, leaving the Indian strike corps free to launch an offensive.
However, the PLA would need to deploy at least six to seven divisions for defense to thwart an Indian offensive. That leaves it just about 20 divisions with which it can attack, which needless to say, is way below the needed combat ratio required for a protracted offensive in mountainous terrain, over tenuous lines of communication.
Good explanation. However, you have not answered the portion you quoted from my post, "China has around 30 divisions deployed against India and the Strike Corps being raised against China may barely be able to support the defensive operation as against launching operations inside China."
Lets say, hypothetically, that the 20 or so Chinese divisions available for launching of offensive are divided in three thrust lines in the North East (I am not talking about actual perception). This means 4-5 divisions in each thrust and some reserves. The Indian response would first come from the holding division and its reserves. Later the Crops reserves would respond. If the offensive is stopped, well enough - if not, the only reserves available then would be the Strike Corps. If this strike corps has already been launched for an offensive inside China, a recoil may come into play.
Therefore, the primary role of the strike corps is likely to remain countering Chinese offensive and not an offensive inside China.