vote
1. tx
add_header
2. receipt(utxo)
fast sync light client protocol
propose collation
verify available
parent_collation_hash
deposite withdraw
exe transaction
3. tx with receipt
random sample

sharding

nodes

challanges

Single-shard takeover attacks

Fraud detection

Cross shard communication

The data availability problem

shard chain 0

shard chain 1

shard chain 100

Block

B0

B1

B2

B3

B4

B5

B6

B7

B8

B9

VMC

collation

collation1

c2

c3

block

block

client

validators
(150)

collator
proposers
prolators

Collation header C1_2
(shard id, period index)

C3_2

C5_4

Cn_m

notary

archival node

Super-full node

archival node

Top-level node

Single-shard node

Light node

decentralizaton

scalability

security

Honest majority

Uncoordinated majority

Coordinated choice

Bribing attacker model

executor