[Cryptography] DAG vs Blockchain

[jamesd at echeque.com]

On 27/01/2018 10:09, bexnews at gmail.com wrote:
> Much hype exists around DAG (directed acyclic graph) in some parts, as 
> an improvement on blockchain crypto because, for one thing, it does away 
> with mining. However isn't mining the thing that incentivizes increased 
> computing power to verify the blockchain and protect against a 51% 
> attack?  Would DAGs be less secure against attackers with lots of 
> computing power *because* there is no mining?


What is supposed to happen is that the blockchain contains metadata 
about merges of data by peers, and thus metadata about what data is 
approved by which peers.

By examining the Dag, one can prove that a majority of peers in good 
standing who have authority over a majority of the value represented by 
the block chain, have approved one past history of the blockchain, and 
not other past histories.

That proof of majority approval of data and metadata gets permanently 
stored in the blockchain, and conflicting versions of the past history 
of the blockchain, together with conflicting approvals of that history 
by minorities of peers, are discarded.