Ensure that the state of a concurrent transaction is repeatable.

[hypercube-lab]

At the moment, there is nothing that prevents a validator from accepting two batches of transactions and processing them in parallel mode. It's conceivable that the debits from the second batch will cause an account to overdraw before the credits from the first batch are credited to the account. If this were to happen, the validator would erroneously vote a legal block as an invalid block, which would have no effect on anyone's account, but would result in a needless rollback and the leader's bond being slashed without justification.

Due to the fact that transactions spanning tick borders are guaranteed to be sequentially consistent, we will most likely only need to submit a Tick to the historian immediately after processing the parallel batch of transactions.

[agnitazudkll]

this would require further research