Counterexample

Pronunciation: /ˈkaʊn.tər.ɪgˌzæm.pl/ Explain

A counterexample disproves or refutes a claim or theorem.^[2]

Examples of Counterexamples

Claim	Counterexample
All students are male.	There exists at least one female student.
Apples are red.	Granny Smith apples are green.
Books are heavy.	There exists at least one book that is not heavy.

References

1. McAdams, David E.. All Math Words Dictionary, counterexample. 2nd Classroom edition 20150108-4799968. pg 50. Life is a Story Problem LLC. January 8, 2015. Buy the book
2. Cupillari, Antonella. Nuts and Bolts of Proof: An Introduction to Mathematical Proofs. 4rd edition. Academic Press. Last Accessed 6/25/2018. Buy the book

Cite this article as:

McAdams, David E. Counterexample. 12/21/2018. All Math Words Encyclopedia. Life is a Story Problem LLC. http://www.allmathwords.org/en/c/counterexample.html.

Revision History

12/21/2018: Reviewed and corrected IPA pronunication. (McAdams, David E.)
6/25/2018: Removed broken links, updated license, implemented new markup, updated GeoGebra apps. (McAdams, David E.)
1/5/2010: Added "References". (McAdams, David E.)
7/11/2008: Added examples. (McAdams, David E.)
3/31/2008: Initial version. (McAdams, David E.)