The perfect active stem is formed in what way?

Question

I am clueless, but i think it is removing i from end of the third principal part

Answer 1

Yes, you are right.

For example, in the famous phrase veni, vidi, vici, there are three verbs in their 1st person, singular, present perfect form. If you remove the "i" from the end of each of these, you have the present perfect stem.

=)