We need to explore more of similar technologies. All of them(Blockchain, DAG, Hashgraph and many more that are going to be discovered in the future) are implementations of a higher abstraction known as DLT(Distributed Ledger Technology). We still need to figure out if Hashgraph is either a sister or a child of DAG technology though.
Keep up the good work!
RE: More Than Blockchains: How Hashgraph & DAGs are Different