I’m sure that’s not possible to do in general (in an algorithmic fashion), since it would solve certain mathematical problems in a flash that aren’t supposed to be solved in polynomial time or even efficiently (like particular halting problems).
I think Tim’s intended meaning was more along the lines of “a language L such that when A is a more likely hypothesis than B, L’s MDL for A is shorter than its MDL for B more often than for any other language”.
I’m sure that’s not possible to do in general (in an algorithmic fashion), since it would solve certain mathematical problems in a flash that aren’t supposed to be solved in polynomial time or even efficiently (like particular halting problems).
You’ll have to hope for something less.
I think Tim’s intended meaning was more along the lines of “a language L such that when A is a more likely hypothesis than B, L’s MDL for A is shorter than its MDL for B more often than for any other language”.