Taming Reverse Mathematics zoo
Reverse Mathematics is a program in the foundations of mathematics. Its results give rise to an elegant classification of theorems of ordinary mathematics based on computability. In particular, the majority of theorems fall into only five categories of which the associated logical systems are dubbed `the Big Five'. Recently, a lot of effort has been directed towards finding exceptional principles, i.e. which fall outside the Big Five categories. The so-called Reverse Mathematics zoo is a collection of such exceptional principles (and their relations). In this paper, we show that uniform versions of the principles from this zoo do fall in line with the Big Five categorisation, i.e. the zoo seems to disappear at the uniform level. In particular, we shall formulate a general template which establishes equivalence between uniform zoo-principles and arithmetical comprehension, the third Big Five category.