[kobieyc]

Something that always trips me up about PoS is how a system that determines the transactional chronology (i.e. sequence of valid blocks) that uses, as a weighted input, the current transactional chronology (valid blocks determine your stake) isn't a logically a circular definition.

[wmf]

Everyone does have to agree out of band on the genesis block or some equivalent. Once you have that, the protocol can progress automatically.