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  1. What is an example of a proof by minimal counterexample?

    Nov 18, 2018 · Assume for contradiction that there is a counterexample to P within some well-ordered set X. Consider the (certainly non-empty) set of all X which are counterexamples to P. This set has a …

  2. big list - Conjectures that have been disproved with extremely large ...

    Jul 23, 2010 · The first counterexample found has 96 vertices. The "least" counterexample known has 54 vertices. Heidetniemi conjecture Chromatic number of tensor product of finite undirected simple …

  3. Using proof by contradiction and a counter example.

    Jul 13, 2017 · This $3$ is also a counterexample to the statement "all natural numbers are even". A proof by contradiction is a proof of a statement by assuming there is a counterexample and then …

  4. "Almost true": non-trivial claims that have exactly one counterexample

    Oct 12, 2024 · Question: What are some non-trivial claims that have exactly one counterexample? Example 1: "There is no Pythagorean triple whose numbers are consecutive terms in a row of …

  5. How are proofs formatted when the answer is a counterexample?

    Suppose it is asked: Prove or find a counterexample: the sum of two integers is odd The fact that 1 + 1 = 2 is a counterexample that disproves that statement. What is the proper format in which to

  6. A counterexample in topology - Mathematics Stack Exchange

    Semi-local simple connectedness is a property that arises in Algebraic Topology in the study of covering spaces, namely, it is a necessary condition for the existence of the universal cover of a

  7. Examples on how to give a proof or a counterexample of a statement

    Apr 7, 2015 · Examples; Prove or give a counterexample of the following statements,with quantifiers: 1) For each non-negative number s, there exists a non-negative number t such that s≥t

  8. Prove that a counterexample exists without knowing one

    Mar 13, 2014 · 0 "Prove that a counterexample exists without knowing one". The existence of continuous nowhere differentiable function can be proved without constructing one. In fact, a "typical" …

  9. reference request - Formal definition of “counterexample ...

    Jul 17, 2016 · What is the preferred formal definition of “counterexample” as in: zero is a counterexample for "every integer is either positive or negative". Where in the literature is the notion …

  10. Constructing a counterexample - Mathematics Stack Exchange

    Jan 24, 2017 · A way to approach the problem of finding a counterexample is to find the values of the atomic propositions that would make the conclusion false. In this case, that would happen if $m$ …