Is TDT accurately described by "CDT + acausal comunication through mutual emulation"?

Communication isn't enough. CDT agents can't cooperate in a prisoner's dilemma if you put them in the same room and let them talk to each other. They aren't going to be able to cooperate in analogous trades across time no matter how much acausal 'communicaiton' they have.

I view TDT as a bit unnatural, UDT is more natural to me (after people explained TDT and UDT to me).

I think of UDT as a decision theory of 'counterfactually equitable rational precommitment' (?controversial phrasing?).

So you (or all counterfactual "you"s) precommit in advance to do the [optimal thing], and this [optimal thing] is defined in such a way as to not give preferential treatment to any specific counterfactual version of you. This is vague. Unfortunately the project to make this less vague is of paper length.

:)

Folks working on UDT, feel free to chime in to correct me if any of above is false.