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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 P within some well-ordered set X X. Consider the (certainly non-empty) set of all X X which are counterexamples to P P. This set …

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

    Jul 23, 2010 · The least counterexample known has order 142108547152020037174224853515625 and p = 5 p = 5. It is the same group that serves counterexample to the Hughes conjecture. Note, that for …

  3. 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" …

  4. Advice on finding counterexamples - Mathematics Stack Exchange

    Apr 1, 2015 · I am reaching out for specific advice on how one should go about finding counterexamples. It seems almost every time I've ever attempted a "find a counterexample" problem, I have to cheat by …

  5. "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 …

  6. 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

  7. 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 …

  8. 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

  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. Ideas of finding counterexamples? - Mathematics Stack Exchange

    Start with the most general example of M M, and the find the condition that all counterexamples of M has to violate, then pick one concrete counterexample from this set of counterexamples: