[pas]

Virtual Voting in hashgraph requires a 2/3 agreement.

Of course PoW provides some protection against sybil attacks, but the reality is that with enough hashpower the network can be overtaken. (Hence why HashGraph is a closed network.)

[EGreg]

What does POW have to do with Hashgraph? It doesn't use POW.

[pas]

oops right, I mixed up IOTA with HashGraph.