BlockDAG
https://blog.daglabs.com/an-introduction-to-the-blockdag-paradigm-50027f44facb
original paper: 2015: Inclusive Block Chain Protocols (Lewenberg, Sompolinsky, Zohar)
CasperLabs
https://techspec.casperlabs.io/technical-details/block-storage/execution-semantics
One of the fundamental design choices that new projects may make is to build a DAG (directed acyclic graph) rather than linear chain (as it is done in Bitcoin or Ethereum). The idea behind building a DAG is that validators may build a blockchain "in parallel" (imagine multiple threads that originate from the same place, run in parallel but join at some point in the future to form a single thread again).
memo
#CasperLabs #Casper