Questions for 6.S897 lecture 8 (Storage 3, 10/06). Email your answers to 6.s897staff@gmail.com. 1) How does Spanner perform transactions that involve records in multiple Paxos groups? Is TrueTime just an optimization here, or required for correctness? 2) Consider one of the invariants that could create inconsistency in TAO, which was that adding or removing certain types of edges (associations) should also add / remove a corresponding "inverse association" (e.g. FOLLOWS and FOLLOWED_BY). Is this invariant I-confluent? If so, why did it lead to inconsistency in TAO?