I haven't dug deep into the implementation, but most of the interesting CRDT stuff seems to be in the "backend" directory in that repo: https://github.com/automerge/automerge/tree/master/backend

In particular the "operations" defined in [1] section 4.2 are defined in this file: https://github.com/automerge/automerge/blob/master/backend/o...

[1] https://www.cl.cam.ac.uk/~arb33/papers/KleppmannBeresford-CR...