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2nd on Google[edit]

A search for Pseudomathematics now has RationalWiki second, after Wikipedia.

ascribing a "metaphysical nature" to mathematics[edit]

there are people who try to ascribe some kind of platonic, metaphysical nature to math, as mathematicians did until the turn of late 19th / early 20th century. others flat out deny or diminish the "viability" of math by (correctly) pointing out that there is no such "platonic truth" behind it.

would those also be classified as pseudomath? if not, where could it fit in on RationalWiki? this seems to be a quite difficult subject to explain... i don't think i'm up to it. who wants to try? — Unsigned, by: / talk / contribs

0.999... = 1[edit]

As promised:

0.999\dots = \frac{9}{10} + \frac{9}{100} + \frac{9}{1000} + \dots
0.999\dots = \frac{9}{10} + \frac{9}{10^2} + \frac{9}{10^3} + \dots
0.999\dots = \sum_{i=1}^\infty 9\cdot\left (\frac{1}{10}\right )^i = \sum_{i=0}^\infty \frac{9}{10}\cdot\left (\frac{1}{10}\right )^i

And since a + ar + ar^2 + ar^3 + \dots is equal to \frac{a}{1-r} for \left\vert r \right\vert < 1 (not proving this here, see Wikipedia's article on geometric series),

\sum_{i=0}^\infty \frac{9}{10}\cdot\left (\frac{1}{10}\right )^i = \frac{0.9}{1 - \frac{1}{10}} = \frac{.9}{.9} = 1

and so 0.999... = 1.

I will now say QED just for extra asshattishness.

QED PacWalker 03:37, 7 April 2015 (UTC)

No proof, only foolhardy definition
0.999\dots = \frac{9}{10} + \frac{9}{100} + \frac{9}{1000} + \dots
0.999\dots = \frac{9}{10} + \frac{9}{10^2} + \frac{9}{10^3} + \dots
0.999\dots = \sum_{i=1}^\infty 9\cdot\left (\frac{1}{10}\right )^i = \sum_{i=0}^\infty \frac{9}{10}\cdot\left (\frac{1}{10}\right )^i
This is also known as the Eulerian Blunder, that is, S = Lim S where
S=0.999\dots = \sum_{i=1}^\infty \frac{9}{10^i} =lim_{n \to \infty} S= lim_{n \to \infty} \sum_{i=1}^n \frac{9}{10^i}=1
Notice there is no proof here of any sort, only a foolhardy definition of 0.999... (an ill-formed object) as 1.— Unsigned, by: Hot sauce / talk / contribs
If they are distinct, give us a number between 0.9 recurring and 1. Show a property of 1 that 0.9 recurring does not satisfy other than appearance. (talk) 04:18, 8 September 2016 (UTC)
And if you have a number between 0.9 recurring and 1 (call it x), then you can construct a decimal of the format 0.9999...9 with a finite number of 9s that's greater than x but less than 0.9 recurring. Wow! Annquin (talk) 16:16, 8 September 2016 (UTC)


 \frac{1}{9}           & = 0.111\dots  \\
 9 \times \frac{1}{9}  & = 9 \times 0.111\dots \\
 1                     & = 0.999\dots

QED. Vive Liberté! 12:35, 21 May 2017 (UTC)

P ?= NP[edit]

This article seriously overstates the practical impact of P = NP. "Polynomial time" is not the same thing as "fast"—O(n^10) may still be polynomial time, but it's exactly as intractable for practical purposes as O(2^n). Simple knowledge of whether or not P is equal to NP has effectively no practical impact on the world. In fact, even giving a concrete algorithm to solve a problem in NP in a very bad polynomial time is not especially impactful. If a proof that P = NP has a practical impact, it will either be secondary due to new mathematics developed for the proof, or because it presents an *extraordinarily* fast (say, O(n^5)) concrete implementation of a particularly impactful algorithm in NP—something which is IMO negligibly probable.

(A proof that P != NP, of course, has no practical impact other than freeing up researchers since that is effectively the current state of the algorithmic art.)

Knuth's opinion is that most likely P = NP, but this fact will not be proved constructively or have any practical impact. (, question 17)

Also, the definition of NP-complete requires only polynomial-time transformations between problems, and while a handful of highly theoretical computer scientists will make a blanket statement that polytime is "fast", they are in a small minority. =) (talk) 01:41, 30 April 2015 (UTC)

Please, add to the article. Cømrade FυzzчCαтPøтαтø (talk/stalk) 01:45, 30 April 2015 (UTC)

My thesis: A form of solving every problem at the same time as verifying it (P=NP) possibly exists. Relative physics, however, sets the upper limit on how fast such problems can be solved, and that limit is finite. As a result, the worst-case of P is O(inf).

Proof of P=NP or P!=NP would currently depend on the progress of Quantum Theory. There is a way to make information travel within information and exceed the speed of light, but reading said information is not yet possible, as it's value collapses even if measured. Still, even if the speed of information exceeds the speed of light, the speed of information cannot be infinite, no matter how fast. Because solving the problem is limited by finite speed, the worst-case polynomial time remains infinite. IViking (talk) 19:40, 31 August 2016 (UTC)

John Gabriel[edit]

This discussion was moved to Essay talk:John Gabriel.

Compiling all the horseshit. Fuzzy "Cat" Potato, Jr. (talk/stalk) 16:39, 23 August 2016 (UTC)

Remaining potentially controversial statements[edit]

(Speaking as an editor)

  1. Uses "crank" ("crank" doesn't appear in referenced text): Today, the professional mathematicians have fully accepted the incompleteness theorems, but a certain breed of crank seems attracted to disproving them.<ref> Yes, the ink is actually black… for some reason.</ref>
  1. Uses "amateur" ("amateur" doesn't appear in referenced text): These attempts have come from amateur<ref>[ Science Forums — Cantor's Diagonal Slash Disproved]</ref> and professional<ref>[ Underwood Dudley — ''Mathematical cranks'']</ref> mathematicians alike.
  1. Uses "amateur" ("amateur" doesn't appear in referenced text): In the decade since 2000, well-intentioned amateurs have attempted a whole host of attempts to solve these problems, especially the Riemann Hypothesis.<ref name="Riemann">[ Proposed (dis)proofs of the Riemann Hypothesis]</ref>

Crank is questionable; the others are probably fine. Elsewhere, the article doesn't talk about people at all.

None of these are references to Gabriel -- they are just elsewhere in the article. oʇɐʇoԀʇɐϽʎzznℲ (talk/stalk) 01:43, 20 August 2016 (UTC)

The relationship between pseudomathematics and mathematics[edit]

Has any attempt at 'disproving'/'explaining the flaws in the particular example of' pseudomathematics proved useful for actual mathematics? (talk) 09:58, 21 May 2017 (UTC)