incompleteness
121Set-theoretic definition of natural numbers — Several ways have been proposed to define the natural numbers using set theory.The contemporary standardIn standard (ZF) set theory the natural numbersare defined recursively by 0 = {} (the empty set) and n +1 = n ∪ { n }. Then n = {0,1,..., n… …
122Interesting number paradox — The interesting number paradox is a semi humorous paradox that arises from attempting to classify numbers as interesting or dull . The paradox states that all numbers are interesting. The proof is by contradiction: if there were uninteresting… …
123Requirement — In engineering, a requirement is a singular documented need of what a particular product or service should be or do. It is most commonly used in a formal sense in systems engineering or software engineering. It is a statement that identifies a… …
124Dialetheism — is the view that some statements can be both true and false simultaneously. More precisely, it is the belief that there can be a true statement whose negation is also true. Such statements are called true contradictions , or dialetheia.… …
125Absolute geometry — is a geometry based on an axiom system for Euclidean geometry that does not assume the parallel postulate or any of its alternatives. The term was introduced by János Bolyai in 1832.[1] It is sometimes referred to as neutral geometry,[2] as it is …
126Decidability (logic) — In logic, the term decidable refers to the decision problem, the question of the existence of an effective method for determining membership in a set of formulas. Logical systems such as propositional logic are decidable if membership in their… …
127Pseudomathematics — is a form of mathematics like activity that does not work within the framework, definitions, rules, or rigor of formal mathematical models. While any given pseudomathematical approach may work within some of these boundaries, for instance, by… …
128Saudade — articleissues article = y refimprove = August 2008 original research = March 2008Saudade (singular) or saudades (plural) (pronounced|sawˈdade in Galician, pronounced|sawˈdadɨ in European Portuguese and IPA| [sawˈdadʒi] or IPA| [sawˈdadi] in… …
