Multiple party contracts, do it in the sandbox

Multi-sig wallets — short for multiple signature — are especially popular with cryptocurrency startups and other collective groups because they require more than one person to agree before any currency gets moved around. It's a safeguard against rogue employees who might run off with the cryptocurrencies for their own gain.

From bitcoin'

This is all in smart contracts, not pure cash.  The  Parity bug that locked up the ethereum funds was doing this and is in permanent wait for another signature. 

I pure cash the no arb condition means all trading runs to completion. Whatever the bots are trading, they already have the proper authorization. So, Coinbase  run trades to completion, Coinbase is in pure cash.  This layering concept between pure cash and smart contracts makes a lot of sense in this iteration of the sandbox. 

The distinction, one has indexable events,  the other does not.  We should get this iteration up and running, then turn our Russian mathematicians into the task of trading contracts themselves, extending no arb farther into smart contracts.  The links between smart and pure are the ledger services.