an example that refutes an assertion or claim.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
How to use counterexample in a sentence
He thought the five-cycle case, in particular, would be the counterexample demonstrating that very point.New Proof Reveals That Graphs With No Pentagons Are Fundamentally Different | Steve Nadis | April 26, 2021 | Quanta Magazine
Mathematicians often find minimal counterexamples easier to work with because they can focus on those parts of the graph that are relevant to the problem at hand and temporarily ignore the rest.New Proof Reveals That Graphs With No Pentagons Are Fundamentally Different | Steve Nadis | April 26, 2021 | Quanta Magazine
Gardam’s discovery of a counterexample to the unit conjecture is oddly reassuring, Kropholler said, because it suggests that this hard work was really needed.
So one immediate question is whether there are counterexamples to be found using other number systems such as the real or complex numbers.
For Gardam, his discovery is the culmination of years spent hunting for intriguing counterexamples in algebra.
British Dictionary definitions for counterexample
an example or fact that is inconsistent with a hypothesis and may be used in argument against it
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012