How is SCP different from Ripple's UNLs? I sort of understand that nodes make up slices, which can vary in size. For example, if I send Lumens from Account A to Account B, a quorum from A to B must form, right?
I understand quorum intersection in that every two quorums must share a node but what if a quorum doesn't share a node with another quorum? Is it no longer considered a quorum? How is this system protected from a sybil attack?