Duplex micropayment channels

Duplex micropayment channels are bi-directional micropayment channels that use deincrementing relative time locks to ensure the latest state is the first that can be confirmed. Compared to bi-directional LN-Penalty channels, they allow a much more limited number of state updates but safely support more than two participants.

This topic description is a stub. We would welcome a pull request providing more background information about the topic.