If F, m and a are true real numbers, its un-computable (can't code it in TM) and not even considered by Solomonoff induction, so here.

My point was simply that MWI is not a theory that would pass the 'input begins with string s' criterion, and therefore, is not even part of the sum at all.

It's pretty hilarious, the explanation is semi okay, but implied is that Solomonoff induction is awesome, and the topic is hard to think about, so people substitute "awesome" for Solomonoff induction, then all the imagined implications end up "not even wrong". edit: also someone somehow thinks that Solomonoff induction finds probabilities for theories, while it just assigns 2^-length as probability for software code of such length, which is obviously absurd when applied to anything but brute force generated shortest pieces of code, because we don't get codes to their minimum lengths (thats uncomputable) and the hypothesis generation process can have e.g. bloat up factor of 10 (plausible) or even a quadratic blow up factor, making the 2^-length prior be much much too strongly discriminating against actual theories in favour of simply having the copy of the data stored inside.