Quantum Immortality/Suicide
This doesn't seem to fit. There isn't anything about Quantum Immortality that requires UDT (except in as much as any decision requires at least some kind of decision theory). The difficulty (and common confusion) is around translating primitive preference-intuitions into preference-beliefs about wavefunctions or branches. Once the values are given, both CDT and EDT will just result in the same decision that UDT would make (unless the specific decision also combines one of the other issues UDT is required for.)
There isn't anything about Quantum Immortality that requires UDT (except in as much as any decision requires at least some kind of decision theory). The difficulty (and common confusion) is around translating primitive preference-intuitions into preference-beliefs about wavefunctions or branches. Once the values are given, both CDT and EDT will just result in the same decision that UDT would make (unless the specific decision also combines one of the other issues UDT is required for.)
I think UDT makes it possible to understand what decisions are, and how wavefunctions can depend on one's decisions. Before I came up UDT ideas, this was really unclear to me, and I had considered some other decision theory approaches where Quantum Immortality was sort of baked in. For example I had the idea that the wavefunction couldn't be changed, but when you make decisions, you're choosing which branch of the wavefunction your consciousness continues into.
Is there a post on the relative strengths/weaknesses of UDT and TDT? I've searched but haven't found one.
This reminds me of the debate between programmers who want to design an elegant system that accomplishes all the desired functions as consequences of a fundamentally simple design, and the programmers who just want to make it work and ship. Depending on the problem you're solving, and the constraints you're working under, I think either approach can be appropriate.
I think the resemblance is only superficial. There is nothing inelegant in treating two wired-in-parallel robotic arms controlled by the same controller, in same way regardless of whenever the controller is same 'real physical object', especially considering that we live in the world where if you have two electrons (or two identical anything), them being separate objects is purely in the eye of the beholder.
The whole point is that you abstract out inelegant details such as whenever the same controllers are physically one system or not. This abstraction is not at odds with mathematical elegance, it is the basis for mathematical elegance. It however is at odd with philosophical compactness-by-confusion. This abstraction does not allow for the notion of causality that was oversimplified to the point of irrelevance.
I noticed that recently I wrote several comments of the form "UDT can be seen as a step towards solving X" and thought it might be a good idea to list in one place all of the problems that helped motivate UDT1 (not including problems that came up subsequent to that post).