"Attack vector by splitting account"

Hi I found this article,

It mentions some type of attack vector? Can someone try and explain what they mean by "splitting an account" being an attack vector. How would you "split an account"? I do not think it is possible to "split an account" or someone would have done it.

I quote from the article:
"We discuss the forging algorithm of Nxt from a probabilistic point of view, and obtain explicit formulas and estimates for several important quantities, such as the probability that an account generates a block, the length of the longest sequence of consecutive blocks generated by one account, and the probability that one concurrent blockchain wins over an- other one. Also, we discuss some attack vectors related to splitting an account into many smaller ones."

So they claim they can do this but has there been a successful attack like the one they mention?

They do go on to say that " Also, it is worth mentioning that Nxt was never successfully attacked during its three years of existence." (the paper is from 2016.).

Its very informative and I understand forging etc. much better now. Its definitely worth a read.

Quote from paper:

"In Section 5 we analyse the probability that a chain forged privately by an attacker is “better” than the legitimate chain (this does not exactly correspond to the current Nxt consensus algorithm, but nevertheless gives some insight about probabilities involved)."

My question: would it improve security if all my active nodes had the EXACT same NXT balance? (I have an NXT clone running separately from NXT) and will announce an airdrop sometime...). Not really public yet.

Can someone try and explain what they mean by "splitting an account" being an attack vector. How would you "split an account"?

Splitting an account means dividing its stake into more than one other accounts, which are controlled by the same user of the original account.

The conclusion of the paper is that splitting the stake into more accounts reduces the chances to generate a block for same amount of coins. This was also discussed here Fairness issue on NXT and its solutions - #4 by petko.petkov . So splitting an account is disadvantageous to the attacker (but not significantly).

My question: would it improve security if all my active nodes had the EXACT same NXT balance? (I have an NXT clone running separately from NXT) and will announce an airdrop sometime...). Not really public yet.

No, it will slightly increase the chances of the attacker if both you and the attacker own a significant percentage of the total stake.

Hi please can you explain what do you mean, if we are the only forgers and "the attacker's stake is percenteage of yours?"

"Percentage of yours" what do you mean, sorry I don't understand, thank you.

Sorry, I meant "a significant percentage" but somehow deleted the significant part. Edited the answer to make it more clear