Talk:Square-free integer: Difference between revisions

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Maybe this should really be [[Square-free integer]]? -- [[User:Waltpohl|Walt Pohl]] 01:40, 2 Mar 2004 (UTC)

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== Square-free → Square-free integer ==

The [[separable polynomial]] page does use the term more generally.

Maybe this should really be [[Square-free integer]]? -- [[User:Charles MatthewsWaltpohl|CharlesWalt MatthewsPohl]] 0801:1740, 2 MarMarch 2004 (UTC)

There's now a:The [[square-freeseparable polynomial]] page, too.does I've changeduse the [[separable polynomial]] page to link there insteadterm ofmore heregenerally.

:[[User:[e-mail] Matthews|[e-mail] Matthews]] 0608:2817, 232 JanuaryMarch 20062004 (UTC)

::There's now a [[square-free polynomial]] page, too. I've changed the [[separable polynomial]] page to link there instead of here.

::[[User:[e-mail]|[e-mail]]] 06:28, 23 January 2006 (UTC)

== Loop quantum gravity section ==

That section does not make much sense. There is something crucial missing from the formulas, but I suspect that it masks a conceptual misapprehension. Is this saying more than "any integer <math>a</math> can be uniquely represented as <math>a=n^2\zeta,</math> where <math>\zeta</math> is square-free"? What is the mathematical statement there, and what is result of some experimental spetroscopy? Unless someone comes up with a really compelling reason, I would propose to remove (or at least move) this section from the article. [[User:Arcfrk|Arcfrk]] 07:32, 10 March 2007 (UTC)

:I have moved the whacky section from the main text to here. [[User:Arcfrk|Arcfrk]] 22:28, 23 March 2007 (UTC)

::'''Application in Loop Quantum Gravity'''

:In the theory of [[loop quantum gravity]] area is an observable operator. As a consequence, the area of a quantum surface is quantized. [[Abhay Ashtekar]] and his colleagues in 1996 found that three incident edges of spins ''j₁'', ''j₂'', and ''j₃'' at a trivalent vertex generate the patch of area:

::<math>a = \ell_P^2 \sqrt{2j_1(j_1+1)+2j_2(j_2+1) - j_3(j_3+1)},</math>

:where <math>\ell_P</math> is the [[Planck length]].

:The spectroscopy of a canonically quantized black hole showed that the area eigenvalue formula fits into the following reduced formula

::<math> \forall n \in N, a = \ell_P^2 n \sqrt{2\zeta} </math>

:(subject to the identification of repeated numbers) where <math>\zeta</math> is a square-free number and <math>\{ \zeta \} = </math> the set of all square-free numbers.

:This helps to expect that black hole Hawking radiation is concentraited on a few lines whose energy is proportional to the square root of square-free numbers.

::'''References'''

::* [http://arxiv.org/abs/hep-th/0607081 Spectroscopy of a Canonically Quantized Black Hole]

::<!-- Template:Unsigned --><small class="autosigned">—&nbsp;Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[User:Arcfrk|Arcfrk]] ([[User talk:Arcfrk#top|talk]] • [[Special:Contributions/Arcfrk|contribs]]) 22:28, 23 March 2007 (UTC)</small>

::There is a proof in the reference for this. As far as I learn, the proof is simple and neat anyway. Any number is decomposed into its prime numbers, each to an odd or even power. The even power comes up to make a square number, the odd factors make up a square-free number. ([[User:129.97.58.55|129.97.58.55]] 22:31, 26 March 2007 (UTC))

== We have a lot of equivalent characterizations already, ==

I know, but here's another:The number of divisors of a squarefree integer is a power of two.[[User:Richard L. Peterson|Rich]] 06:55, 1 November 2006 (UTC)

:How about 8? Its 4=2^2 factors are 1, 2, 4 and 8, but it is not square-free. [[User:128.101.10.146|128.101.10.146]] 23:22, 7 June 2007 (UTC)

::Indeed. Having a number of divisors that is a power of two is a necessary, but not sufficient, condition for being squarefree. [[User:Doctormatt|Doctormatt]] 23:39, 7 June 2007 (UTC)

== Square-free test ==

Is it known something about the complexity of testing if an integer is square-free? Maybe some relation with [[Primality test]]. [[Special:Contributions/193.144.198.250|193.144.198.250]] ([[User talk:193.144.198.250|talk]]) 11:28, 11 March 2014 (UTC)

== 1 as a squarefree integer ==

I cannot understand: whether today any mathematicians consider squarefree numbers without 1 or not. Is it possible (for contemporary scientists) to define "squarefree number" as "a number that is the product of integer number of different primes"? --[[User:Tamtam90|Tamtam90]] ([[User talk:Tamtam90|talk]]) 22:06, 5 August 2017 (UTC)

: Square free numbers may be defined as products of primes that are all different. This definition is equivalent with the one that is given in the first sentence of the article, as 1 is the [[empty product]] of primes. Thus, presently, 1 is always defined to be square free. [[User:D.Lazard|D.Lazard]] ([[User talk:D.Lazard|talk]]) 08:30, 6 August 2017 (UTC)

:: Thank you for your answer. I think I'd ask about this subject Mr. John Derbyshire and Mr. Dennis Hejhal. --[[User:Tamtam90|Tamtam90]] ([[User talk:Tamtam90|talk]]) 23:57, 7 August 2017 (UTC)

== squarefull and squareful ==

This business about having two completely different definitions for « squarefull » and « squareful » (according to the number of « l » of the word) is not confirmed by common practice in mathematical publications. A search in MathSciNet with

"squarefull integer" or "squarefull integers", anywhere, yields 10 articles, and with "squarefull number" or "squarefull numbers", anywhere, yields 21 articles. The same searches with only one « l » in « squareful » yield 0, resp. 8 articles. In the last output the definition of « Squareful » is the same as that of « squarefull », except in one single article, in which it is indeed defined as « not squarefree » (but for which the reviewer nevertheless writes « squarefull » with two « l » in his review…).

Now OEIS is a wiki, and provides zero source for its page [http://oeis.org/wiki/Squareful_numbers]; as for the page [https://mathworld.wolfram.com/Squareful.html] of Mathworld, it provides as unique reference 4 sequences from … OEIS (which in passing do not include the one on « squareful numbers », and all of which explicitly concern « non squarefree numbers » , and not « squareful numbers ») .--[[User:Sapphorain|Sapphorain]] ([[User talk:Sapphorain|talk]]) 07:01, 24 August 2020 (UTC)

:: OK, leave it out. [[User:Bubba73|Bubba73]] ^{[[User talk:Bubba73|You talkin' to me?]]} 16:46, 24 August 2020 (UTC)

== Moved without any discussion ==

This page has been moved without discussion from {{noredirect|square-free integer}} to [[squarefree number]]. The new title is confusing, as "square-free" is nonsensical when applied to numbers that are not integers. So, I'll ask to revert this move. [[User:D.Lazard|D.Lazard]] ([[User talk:D.Lazard|talk]]) 20:36, 24 September 2021 (UTC)

: I *think* I've always seen it called "number". [[User:Bubba73|Bubba73]] ^{[[User talk:Bubba73|You talkin' to me?]]} 01:52, 25 September 2021 (UTC)

== Broken redirect ==

Cube-free integer redirects to a section of this page that doesn’t exist?? [[Special:Contributions/117.198.96.34|117.198.96.34]] ([[User talk:117.198.96.34|talk]]) 07:01, 5 February 2024 (UTC)

: You are right. I shall nominate the page for deletion. [[User:JBW|JBW]] ([[User talk:JBW|talk]]) 15:20, 5 February 2024 (UTC)

: I have now listed this at [[Wikipedia:Redirects_for_discussion/Log/2024_February_5#Cube free integer]]. You may contribute to the discussion if you wish to. [[User:JBW|JBW]] ([[User talk:JBW|talk]]) 15:37, 5 February 2024 (UTC)

::Okay, starting this by saying I am the original topic creator at a different ___location..

::Could we add a section for (x^n-free integers for n higher than 2)?

::Would make the redirect make more sense in my opinion. [[Special:Contributions/122.171.18.2|122.171.18.2]] ([[User talk:122.171.18.2|talk]]) 11:34, 7 February 2024 (UTC)