# gwern's Shortform

post by gwern · 2021-04-24T21:39:14.128Z · LW · GW · 5 comments## 5 comments

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## comment by gwern · 2021-04-24T21:47:50.065Z · LW(p) · GW(p)

*Humanities satirical traditions*: I always enjoy the CS/ML/math/statistics satire in the annual SIGBOVIK and Ig Nobels; physics has Arxiv April Fools papers (like "On the Impossibility of Supersized Machines") & journals like Special Topics; and medicine has the BMJ Christmas issue, of course.

What are the equivalents in the humanities, like sociology or literature? (I asked a month ago on Twitter and got zero suggestions...)

## comment by gwern · 2021-04-24T21:39:16.652Z · LW(p) · GW(p)

*Normalization-free Bayes*: I was musing on Twitter about what the simplest possible still-correct
computable demonstration of Bayesian inference is, that even a
middle-schooler could implement & understand. My best candidate so far
is ABC Bayesian inference*: simulation + rejection, along with the
'possible worlds' interpretation.

Someone noted that rejection sampling is simple but needs
normalization steps, which adds complexity back. I recalled that
somewhere on LW many years ago someone had a comment about a Bayesian
interpretation where you don't need to renormalize after every
likelihood computation, and every hypothesis just decreases at
different rates; as strange as it sounds, it's apparently formally equivalent. I *thought* it was by Wei Dai, but I can't seem to refind
it because queries like 'Wei Dai Bayesian decrease' obviously pull up
way too many hits, it's probably buried in an Open Thread
somewhere, my Twitter didn't help, and Wei Dai didn't recall it at all when I asked him. Does anyone remember this?

* I've made a point of using ABC in some analyses simply because it amuses me that something so simple still works, even when I'm sure I could've found a much faster MCMC or VI solution with some more work.

Incidentally, I'm wondering if the ABC simplification can be taken further to cover subjective Bayesian decision theory as well: if you have sets of possible
worlds/hypotheses, let's say discrete for convenience, and you do only
penalty updates as rejection sampling of worlds that don't match the
current observation (like AIXI), can you then implement decision
theory normally by defining a loss function and maximizing over it? In
which case you can get Bayesian decision theory without probabilities,
calculus, MCM, VI, etc or anything more complicated than a list of
numbers and a few computational primitives like `coinflip()`

.

## ↑ comment by Wei_Dai · 2021-04-25T00:43:07.008Z · LW(p) · GW(p)

Doing another search, it seems I made at least one comment that is somewhat relevant, although it might not be what you're thinking of: https://www.greaterwrong.com/posts/5bd75cc58225bf06703751b2/in-memoryless-cartesian-environments-every-udt-policy-is-a-cdt-sia-policy/comment/kuY5LagQKgnuPTPYZ [LW(p) · GW(p)]

## comment by gwern · 2021-04-24T22:09:28.493Z · LW(p) · GW(p)

*2-of-2 escrow*: what is the exploding Nash equilibrium? Did it really originate with NashX? I've been looking for the history & real name of this concept for years now and have failed to refind it. Anyone?