To clarify the misconception of “gossip about gossip” related to its use in the PARSEC algorithm, people should know, that this idea is very old! In fact it is already used in the 1982 paper “The Byzantine Generals Problem” By L. Lamport, R. Shostak and M. Pease in their algorithm #2 called “Sm(.)” in that paper.
Quote from that paper: “[…] In our algorithm, the commander sends a signed order to each of his lieutenants. Each lieutenant then adds his signature to that order and sends it to the other lieutenants, who add their signatures and send it to others, and so on. This means that a lieutenant must effectively receive one signed message, make several copies of it, and sign and send those copies […]”
If this is done in a randomized gossip fashion, hashgraph branded it as
“gossip-over-gossip”. It is a key stone in many byzantine fault tollerant systems, as it is an efficient way to handel malicious nodes.
The new idea of hashgraph is virtual voting, but there is no such thing in PARSEC as it uses a different consensus mechanis and a global concrete coin.