I'm the first author of the paper, happy to answer any questions

off topic: Regarding Figure 8: "a graph with 10 nodes, each having 4 neighbors and no two shards requiring more than 2 hops for cross-shard communication". This can be achieved with only 3 neighbors (Petersen graph) https://en.wikipedia.org/wiki/Petersen_graph

More about this here: https://en.wikipedia.org/wiki/Table_of_the_largest_known_gra...

I've learned a lot from Alex just by working through these diagrams with him. Brilliant thinking that I hope will remove some of the current barriers in blockchain.

FYI: found a pretty neat paper describes a new sharding design for proof-of-stake blockchains

I think the company that's building it just announced or opened up a beta program too

Nightshade specifics start on page 21 (section 3). The first bit is just an intro on sharding.

The fishermans' drawing is a nice touch

I agree.

Handling the speed and validation trade off