- Dystopia (Wikipedia)
A dystopia (from Ancient Greek δυσ (dus) ‘bad’, and τόπος (tópos) ‘place’), also called a cacotopia or anti-utopia, is a community or society that is extremely bad or frightening. It is often treated as an antonym of utopia, a term that was coined by Sir Thomas More and figures as the title of his best known work, published in 1516, which created a blueprint for an ideal society with minimal crime, violence, and poverty. The relationship between utopia and dystopia is in actuality, not one simple opposition, as many utopian elements and components are found in dystopias as well, and vice versa.
- Natural number (Wikipedia)
In mathematics, the natural numbers are the numbers 1, 2, 3, etc., possibly including 0 as well. Some definitions, including the standard ISO 80000-2, begin the natural numbers with 0, corresponding to the non-negative integers 0, 1, 2, 3, …, whereas others start with 1, corresponding to the positive integers 1, 2, 3, … Texts that exclude zero from the natural numbers sometimes refer to the natural numbers together with zero as the whole numbers, while in other writings, that term is used instead for the integers (including negative integers). In common language, particularly in primary school education, natural numbers may be called counting numbers to intuitively exclude the negative integers and zero, and also to contrast the discreteness of counting to the continuity of measurement—a hallmark characteristic of real numbers.