Stijn Vermeeren (Leeds)
Permutation and Injection Randomness

Computable randomness is a central notion in algorithmic randomness, which is usually defined using "betting strategies" for betting on the digits of an infinite sequence. The notion can be strengthened by allowing strategies that bet on the digits in a non-monotonic order, e.g. in an order given by a computable permutation or injection.

In this seminar, I will first prove that for total betting strategies, permutation betting strategies are not more powerful than ordinary betting strategies; i.e. total permutation randomness is equivalent with computable randomness. However, injection betting strategies are more powerful, which I will show by giving my own construction of a partial computable random sequence that is not total injection random.