Questions tagged [solution-verification]

For posts looking for feedback or verification of a proposed solution. "Is my proof correct?" is too broad or missing context. Instead, the question must identify precisely which step in the proof is in doubt, and why so. This should not be the only tag for a question, and should not be used to circumvent site policies regarding duplicate questions.

This tag should be used when you have a proposed solution to a problem and have specific concerns or doubts about the validity of that solution. A question with this tag should include an explanation for why the argument presented is not convincing enough. Further discussion on using this tag can be found in the Mathematics Meta questions (1) and (2).

Answers to questions tagged look first and foremost to check that the solution is right, and to comment upon the approach taken by the author of the question. If the proposed solution is wrong, a good answer would explain where or how mistakes were made, and possibly give or sketch a correct solution instead.

If the proposed solution is correct, an answer would ideally provide further evidence to back the answerer's opinion. These could include a clearer rewriting of the given argument, alternative arguments, generalizations of the proven result, or careful consideration of unexpected subtle points. Users looking to write answers can find further discussion in this Mathematics Meta post.

21426 questions
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Verification of $\forall x \in \mathbb{R},(\bigg \lfloor \frac{\lfloor \frac{x}{2} \rfloor}{2} \bigg \rfloor = \lfloor \frac{x}{4} \rfloor )$

Question This question was answered elsewhere, but I found the answer unsatisfying, mostly due to the amount of steps skipped. Maybe I've over complicated things, but just wondering if I'm going about things correctly. To Prove $\forall x \in…
Aaron
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Explicit bijection between $\mathbb{N}$ and $\mathbb{N}^2$

I am having some trouble writing a bijection between $\mathbb{N} = \{0, 1, 2, 3, \ldots\}$ and $\mathbb{N}^2$, particularly using the definition that $\mathbb{N}$ includes $0$. (Otherwise, it is straightforward.) Here is what I have so…
John P.
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Is it possible to represent 3 positive numbers each as the difference of semiperimeter and one of the side of a triangle

It is possible to represent three positive numbersas sum of two numbers from a set of 3 numbers. But is it possible represent 3 positive numbers let $a,b,c $ as $s-x,\ s-y,\ s-z$ where $x,y,z$ are the sides of a triangle and $s $ is the…
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If $x_n$ converges to $L \in \mathbb{R}$ with $x_n \leq B$ for all $n \in \mathbb{N}$, then $\lim_{n\to\infty} x_n = L \leq B$

Proof (by contradiction). Suppose $x_n$ converges to $L \in \mathbb{R}$ with $x_n \leq B$ for all $n \in \mathbb{N}$ and that $\lim_{n\to\infty} x_n = L > B$. Then, since $x_n$ converges to $L > B$, it follows that $(\forall \varepsilon > 0)$…
thomasbdc
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Why can you compute $\dfrac{d}{dx}{x^x} $ by holding constant the base + exponent?

Pls discuss just the method below, and refrain from other methods. The alternate solution below looks wrong to me, because both the exponent and base are $x$! So how can you possibly pretend or playact that they're not, and treat the exponent and…
user53259
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A Quasi-Concave Function and Its Convex Upper Contour Set (Proof Verification)

I'm practicing my proof-writing and was hoping you could let me know if this proof looks good. I would like to know if the proof is incorrect, if there are parts that are overly wordy/complicated, or if I'm missing some element of a proof that is…
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Condensation Points and Perfect Sets (Proof Verification)

I'm practicing my proof-writing and was hoping you could let me know if this proof looks good. I would like to know if the proof is incorrect, if there are parts that are overly wordy/complicated, or if I'm missing some element of a proof that is…
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Proving Compactness Without the Heine-Borel Theorem (Proof Verification)

I'm practicing my proof-writing and was hoping you could let me know if this proof looks good. I would like to know if the proof is incorrect, if there are parts that are overly wordy/complicated, or if I'm missing some element of a proof that is…
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Limit Points and Open/Closed Sets (Proof Verification)

I'm practicing my proof-writing and was hoping you could let me know if this proof looks good. I would like to know if the proof is incorrect, if there are parts that are overly wordy/complicated, or if I'm missing some element of a proof that is…
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Are the Irrational Reals Countable? (Proof Verification)

I'm practicing my proof-writing and was hoping you could let me know if this proof looks good. I would like to know if the proof is incorrect, if there are parts that are overly wordy/complicated, or if I'm missing some element of a proof that is…
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Dot Products of K-Vectors That Are Not Equal to Zero (Proof Verification)

I'm practicing my proof-writing and was hoping you could let me know if this proof looks good. I would like to know if the proof is incorrect, if there are parts that are overly wordy/complicated, or if I'm missing some element of a proof that is…
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Monotone Sequences that are Bounded Above (Proof Verification)

I'm practicing my proof-writing and was hoping you could let me know if this proof looks good. I would like to know if the proof is incorrect, if there are parts that are overly wordy/complicated, or if I'm missing some element of a proof that is…
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Proving a Bijection (Proof Verification)

I'm practicing my proof-writing and was hoping you could let me know if this proof looks good. I would like to know if the proof is incorrect, if there are parts that are overly wordy/complicated, or if I'm missing some element of a proof that is…
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Is this proof correct convergence

I'm trying to show that $(a_{n}) \to -\infty \Leftrightarrow (-a_{n}) \to \infty$ Attempt $(\Rightarrow)$: We have $(a_{n}) \to -\infty$. By definition this means, for all $C < 0$ there exists $N$ such that $a_{n} < C$ for all $n > N$. Therefore we…
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Prove the Positive Orthant is Open (Proof Verification)

I'm practicing my proof-writing and was hoping you could let me know if this proof looks good. I would like to know if the proof is incorrect, if there are parts that are overly wordy/complicated, or if I'm missing some element of a proof that is…