Unhashed source : greet explanation about LCV
Dan Larimer source :
https://medium.com/eosio/eosio-dawn-3-0-now-available-49a3b99242d7
"Especially this paragraph"
Inter-blockchain communication is the ultimate scalability feature — the holy grail — that the industry has been searching for with proposals such as side-chains, plasma, and sharding. Inter-blockchain communication enables one blockchain to verify the authenticity of an event on another blockchain in a provably secure manner. The goal is for inter-blockchain communication to be as secure as intra-chain communication between smart contracts and we think we have achieved that goal.
From our perspective, inter-blockchain communication is nothing more than having the ability to implement a light client as a smart contract. A light client is able to validate transactions from a blockchain without having to process the entire blockchain. This in turn means building a proof-of-stake blockchain with efficient and secure light-client validation. Light-client validation must therefore be factored into the protocol design, as it is almost impossible to implement after the fact.