Consensus in IOTA is no longer decoupled from the transaction making process: it’s an intrinsic part of it, and it’s what enables IOTA to scale without any transaction fees. But how is consensus achieved in offline transactions?
Since IOTA is partition tolerant, it is possible to have txs without referring immediately to the main tangle. This feature is crucial when it comes to fog or mist computing, I think. In this case I mean the partitioning which is key in being adaptive to the requirements of an asynchronous IoT environment. Where there is no „always-on connectivity“, as such you need to be able to make transactions and secure data even in an offline environment. IOTA makes it somehow possible for a cluster of devices to branch off and make transactions in an offline environment which later refer to the main tangle.