Could you recommend books or websites where I could learn about this? Thanks.
Not exactly. It is buried in algorithmic information theory and directly related to a very important but esoteric measure called predictive error complexity. The best (and only) explanatory book on that mathematics that I am aware of is Marcus Hutter's. While I find it to be an easy read, you will need to be thoroughly familiar with information and computational theory, at least of the level of Li and Vitanyi, or you will not be able to make heads or tails of it. You can find some related stuff on the web (e.g. AIXI models) that will point you in the right direction and will be no worse than the book in terms of ease of readability. The construction has been described by some as the result of taking Bayes' theorem to its logical mathematical extreme.
It is deeply elegant and remarkably simple in construction, and one of the neatest developments in math in a long time, but it also requires grokking computational and information theory at a pretty deep level to understand its significance and the number of facets it has.
To be brutally honest, from a standing start it would probably take two years of serious study to grok it. It is not that it is so difficult, but that very few people have the mathematics foundation to make grokking it easy. Really bright people with a solid theoretical background can usually wrap their head around the basic theory in a matter of months.