Equivalence of random coinflips view and minimal programs view

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Two of the several ways of viewing the deterministic variant of Solomonoff induction are:

  • The "random coinflips view": Given a monotone Turing machine, we feed the machine with random data (such as from unbiased coinflips). The probability of string x is then the probability that the machine outputs something starting with x.
  • The "minimal programs view": Given a monotone Turing machine T, the minimal programs producing x are those programs p such that T(p)=x* (i.e. T when run with p produces an output starting with x) and such that no proper prefix of p produces x (i.e. if qp then T(q)x*). This view then says that to get the probability of x, we add up all the minimal programs weighted by length as follows: for each program p we assign the weight 2|p|, where |p| is the length of p. Thus the measure is p2|p|, where the sum is taken over all minimal programs p producing x.

These two views turn out to be equivalent in the sense that .