X*Y >= K
Pair of any two ERC20 coins: (improvement over v1 where only ERC20/ETH pair is supported) + Router contract
Flash Swaps: (atomic transaction, bundle everything within 1 transaction):
30bps transaction cost (potentially 5bps fee)
Price Oracle: use price at beginning/end of a block / TWAP
Reference:
https://uniswap.org/whitepaper.pdf
https://github.com/Uniswap/v2-periphery/blob/master/contracts/examples/ExampleFlashSwap.sol