To install click the Add extension button. That's it.

The source code for the WIKI 2 extension is being checked by specialists of the Mozilla Foundation, Google, and Apple. You could also do it yourself at any point in time.

4,5
Kelly Slayton
Congratulations on this excellent venture… what a great idea!
Alexander Grigorievskiy
I use WIKI 2 every day and almost forgot how the original Wikipedia looks like.
Live Statistics
English Articles
Improved in 24 Hours
Added in 24 Hours
What we do. Every page goes through several hundred of perfecting techniques; in live mode. Quite the same Wikipedia. Just better.
.
Leo
Newton
Brights
Milds

Minimal counterexample

From Wikipedia, the free encyclopedia

In mathematics, a minimal counterexample is the smallest example which falsifies a claim, and a proof by minimal counterexample is a method of proof which combines the use of a minimal counterexample with the ideas of proof by induction and proof by contradiction.[1][2] More specifically, in trying to prove a proposition P, one first assumes by contradiction that it is false, and that therefore there must be at least one counterexample. With respect to some idea of size (which may need to be chosen carefully), one then concludes that there is such a counterexample C that is minimal. In regard to the argument, C is generally something quite hypothetical (since the truth of P excludes the possibility of C), but it may be possible to argue that if C existed, then it would have some definite properties which, after applying some reasoning similar to that in an inductive proof, would lead to a contradiction, thereby showing that the proposition P is indeed true.[3]

If the form of the contradiction is that we can derive a further counterexample D, that is smaller than C in the sense of the working hypothesis of minimality, then this technique is traditionally called proof by infinite descent. In which case, there may be multiple and more complex ways to structure the argument of the proof.

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.

YouTube Encyclopedic

  • 1/3
    Views:
    1 554
    334
    1 336
  • Proof by Minimum Counterexample
  • Math 308 Lecture 11 - Induction, Minimum Counterexample and Intro to Strong Induction
  • Proof by Counterexample

Transcription

Examples

The minimal counterexample method has been much used in the classification of finite simple groups. The Feit–Thompson theorem, that finite simple groups that are not cyclic groups have even order, was[when?] based on the hypothesis of some, and therefore some minimal, simple group G of odd order. Every proper subgroup of G can be assumed a solvable group, meaning that much theory of such subgroups could be applied.

Euclid's proof of the fundamental theorem of arithmetic is a simple proof which uses a minimal counterexample.[4][5]

Courant and Robbins used the term minimal criminal for a minimal counter-example in the context of the four color theorem.[6]

References

  1. ^ Chartrand, Gary, Albert D. Polimeni, and Ping Zhang. Mathematical Proofs: A Transition to Advanced Mathematics. Boston: Pearson Education, 2013. Print.
  2. ^ Klipper, Michael (Fall 2012). "Proof by Minimum Counterexample" (PDF). alpha.math.uga.edu. Archived from the original (PDF) on 2018-04-17. Retrieved 2019-11-28.
  3. ^ Lewis, Tom (Fall 2010). "§20 Smallest Counterexample" (PDF). math.furman.edu. Retrieved 2019-11-28.
  4. ^ "The Fundamental Theorem of Arithmetic | Divisibility & Induction | Underground Mathematics". undergroundmathematics.org. Retrieved 2019-11-28.
  5. ^ "The fundamental theorem of arithmetic". www.dpmms.cam.ac.uk. Retrieved 2019-11-28.
  6. ^ Richard Courant; Herbert Robbins (1996). What is Mathematics? (2nd ed.). Oxford: Oxford University Press. ISBN 9780195105193. Here: p.495: "Since there is no point in making bad maps bigger, we go the opposite way and look at the smallest bad maps, colloquially known as minimal criminals."
This page was last edited on 26 September 2023, at 21:43
Basis of this page is in Wikipedia. Text is available under the CC BY-SA 3.0 Unported License. Non-text media are available under their specified licenses. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc. WIKI 2 is an independent company and has no affiliation with Wikimedia Foundation.