Negation of punctual verbs

[jl168]

I want to ask whether the negation of punctual verbs like "知る" and "忘れる" should be "知らない" and "忘れない" or "知っていない" and "忘れていない".
Thanks a lot in advance!

 

[Toritoribe]

Those forms are all correct, but the meanings are different. 忘れていない is the negative form of the present tense 忘れている, whereas 忘れない is for the future tense or expressing the speaker's will.
知る is a bit special verb. 知らない is mostly used for the present tense unlike other instantaneous verbs. 知っていない is for specific contexts or structures.