Search results
Results from the WOW.Com Content Network
In logic a counterexample disproves the generalization, and does so rigorously in the fields of mathematics and philosophy. [1] For example, the fact that "student John Smith is not lazy" is a counterexample to the generalization "students are lazy", and both a counterexample to, and disproof of, the universal quantification "all students are ...
The assumption that if there is a counterexample, there is a minimal counterexample, is based on a well-ordering of some kind. The usual ordering on the natural numbers is clearly possible, by the most usual formulation of mathematical induction; but the scope of the method can include well-ordered induction of any kind.
It can also be used to construct a counterexample to disprove a proposition that all elements have a certain property. Proof by exhaustion In proof by exhaustion, the ...
Models And Counter-Examples (Mace) is a model finder. [1] Most automated theorem provers try to perform a proof by refutation on the clause normal form of the proof problem, by showing that the combination of axioms and negated conjecture can never be simultaneously true, i.e. does not have a model.
The graph of the Cantor function on the unit interval. In mathematics, the Cantor function is an example of a function that is continuous, but not absolutely continuous.It is a notorious counterexample in analysis, because it challenges naive intuitions about continuity, derivative, and measure.
To form a counterexample, take the smallest non-abelian group B ≅ S 3, the symmetric group on three letters. Let A denote the alternating subgroup , and let C = B / A ≅ {±1 }. Let q and r denote the inclusion map and the sign map respectively, so that
The conjecture was disproved in 1966, with a counterexample involving a count of only four different 5th powers summing to another fifth power: 27 5 + 84 5 + 110 5 + 133 5 = 144 5. Proof by counterexample is a form of constructive proof, in that an object disproving the claim is exhibited.
Conjectures disproven through counterexample are sometimes referred to as false conjectures (cf. the Pólya conjecture and Euler's sum of powers conjecture). In the case of the latter, the first counterexample found for the n=4 case involved numbers in the millions, although it has been subsequently found that the minimal counterexample is ...