# Talk:Main Page

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 Welcome to the general discussion page of $\mathsf{Pr} \infty \mathsf{fWiki}$.Please add any new discussion topics at the bottom of this page.

 Main Talk Page Archives Archive 1: $-\infty$ to Sept 24/08 Archive 2: Sept 25/08 to Dec 20/08 Archive 3: Dec 21/08 to Feb 21/09 Archive 4: Feb 22/09 to Jun 14/09 Archive 5: Jun 15/09 to Feb 21/10 Archive 6: Feb 22/10 to May 10/11 Archive 7: May 11/11 to Mar 28/12 Archive 8: Mar 29/12 to Oct 10/12 Archive 9: Oct 11/12 to May 18/13 Archive 10: May 27/13 to Oct 18/14 Archive 11: Oct 27/14 to Dec 21/15 Archive 12: Dec 22/15 to Aug 1/17 Archive 13: Aug 2/17 to May 8/18

## Dirichlet Series

So I'm working on expanding the Dirichlet series category and adding all the important theorems and such; however, much of theory can be proven in the broader sense of general Dirichlet series so I believe the current Categories are unsuitable. I'm planning on doing some restructuring with General Dirichlet Series as a Category and Ordinary Dirichlet Series as a subcategory, with the general theorems having a 'subpage' for the form the theorem takes in the ordinary sense. Let me know if I mess anything up, or if the wiki would prefer a different method of doing this. --AliceInNumberland (talk) 22:23, 26 May 2018 (EDT)

Categories are good, I think.
One point to bear in mind: try to provide a source for your work, particularly if you are adding definitions. Look at the "Sources" section at the bottom of most pages to see what I mean. Yes, I know that a lot of the pages in this area do not have such sources, but that's because some contributors have in the past preferred not to follow our house rules. Work will of course need to be done to rectify this. --prime mover (talk) 01:13, 27 May 2018 (EDT)
Also, please don't just replace stuff -- if you are expanding on an existing proof, please try and leave the existing shape up as far as possible, including retaining any existing lemmata. If what you are doing is completely new, then add a second proof, and put a comment in the talk page if you need to discuss the viability of the existing one. This is specifically in reference to Dirichlet Series Convergence Lemma, in which reference to the sub-lemma has been lost.
You will notice I have moved your new theorem proof to a new page discussing the general case, subpaged from the original. --prime mover (talk) 03:07, 27 May 2018 (EDT)

## A new shortcut

We have had the $\LaTeX$ shortcut \rd defined for some time which is basically \, \mathrm d. This is convenient to use as the "d" in integrals. But for derivatives it is not so useful, because the extra gap at the start extends the fraction line and makes it look substandard.

Hence I have added \d, which is just \mathrm d. Thus we have, for example, \dfrac {\d y} {\d x} which produces $\dfrac {\d y} {\d x}$.

I have gone through replacing all instances that I can find of \dfrac {\rd y} {\rd x} (and all similar constructs) with their equivalent. --prime mover (talk) 16:30, 2 August 2018 (EDT)

## Volume of paraboloid

After a few long years of search and failure, I was finally able to prove that the volume of a paraboloid is half of its circumscribed cylinder through Cavalieri's Principle.

It is in an analogy to the hemisphere proof, but somewhat harder because you need to use the XY-plane and find the right parabola functions.

In the sketch below, a circle with the green radius shares equal areas with the blue line ring for equal height cross sections.

Can someone please create this page and a 3D-sketch proof? Simcha Waldman (talk) 06:15, 5 August 2018 (EDT)

You are invited to create the page yourself. --prime mover (talk) 06:32, 5 August 2018 (EDT)

## New $\LaTeX$ macros for your convenience and our internal consistency

There are a number of new $\LaTeX$ macros which have been developed recently as a result of a lot of discussion some time back which never ended up happening at the time.

They can be found on the page Symbols:LaTeX Commands/ProofWiki Specific, transcluded here:

 $\AA$ $\quad:\quad$\AA $\qquad$that is: \mathcal A $\Add$ $\quad:\quad$\Add $\qquad$Addition as a Primitive Recursive Function‎ $\adj {\mathbf A}$ $\quad:\quad$\adj {\mathbf A} $\qquad$Adjugate Matrix $\arccot$ $\quad:\quad$\arccot $\qquad$Arccotangent $\arccsc$ $\quad:\quad$\arccsc $\qquad$Arccosecant $\arcsec$ $\quad:\quad$\arcsec $\qquad$Arcsecant $\Area$ $\quad:\quad$\Area $\qquad$Area of Plane Figure $\Arg z$ $\quad:\quad$\Arg z $\qquad$Principal Argument of Complex Number $\Aut {S}$ $\quad:\quad$\Aut {S} $\qquad$Automorphism Group $\BB$ $\quad:\quad$\BB $\qquad$that is: \mathcal B $\Bernoulli {p}$ $\quad:\quad$\Bernoulli {p} $\qquad$Bernoulli Distribution $\BetaDist {\alpha} {\beta}$ $\quad:\quad$\BetaDist {\alpha} {\beta} $\qquad$Beta Distribution $\bigintlimits {\map f s} {s \mathop = 0} {s \mathop = a}$ $\quad:\quad$\bigintlimits {\map f s} {s \mathop = 0} {s \mathop = a} $\qquad$Limits of Integration $\Binomial {n} {p}$ $\quad:\quad$\Binomial {n} {p} $\qquad$Binomial Distribution $\bsDelta$ $\quad:\quad$\bsDelta $\qquad$a vector '$\Delta$' $\bsone$ $\quad:\quad$\bsone $\qquad$vector of ones $\bst$ $\quad:\quad$\bst $\qquad$a vector 't' $\bsv$ $\quad:\quad$\bsv $\qquad$a vector 'v' $\bsw$ $\quad:\quad$\bsw $\qquad$a vector 'w' $\bsx$ $\quad:\quad$\bsx $\qquad$a vector 'x' $\bsy$ $\quad:\quad$\bsy $\qquad$a vector 'y' $\bsz$ $\quad:\quad$\bsz $\qquad$a vector 'z' $\bszero$ $\quad:\quad$\bszero $\qquad$vector of zeros $\map \Card {S}$ $\quad:\quad$\map \Card {S} $\qquad$Cardinality $\card {S}$ $\quad:\quad$\card {S} $\qquad$Cardinality $\Cauchy {x_0} {\gamma}$ $\quad:\quad$\Cauchy {x_0} {\gamma} $\qquad$Cauchy Distribution $\CC$ $\quad:\quad$\CC $\qquad$that is: \mathcal C $\Cdm {f}$ $\quad:\quad$\Cdm {f} $\qquad$Codomain of Mapping $\ceiling {11.98}$ $\quad:\quad$\ceiling {11.98} $\qquad$Ceiling Function $30 \cels$ $\quad:\quad$30 \cels $\qquad$Degrees Celsius $\Char {R}$ $\quad:\quad$\Char {R} $\qquad$Characteristic of Ring, etc. $\Ci$ $\quad:\quad$\Ci $\qquad$Cosine Integral Function $\cis \theta$ $\quad:\quad$\cis \theta $\qquad$$\cos \theta + i \sin \theta $\cl S$ \quad:\quad\cl S \qquadClosure (Topology) $\closedint {a} {b}$ \quad:\quad\closedint {a} {b} \qquadClosed Interval $\cmod {z^2}$ \quad:\quad\cmod {z^2} \qquadComplex Modulus $\conjclass {x}$ \quad:\quad\conjclass {x} \qquadConjugacy Class $\cont {f}$ \quad:\quad\cont {f} \qquadContent of Polynomial $\ContinuousUniform {a} {v}$ \quad:\quad\ContinuousUniform {a} {v} \qquadContinuous Uniform Distribution $\cosec$ \quad:\quad\cosec \qquadCosecant (alternative form) $\Cosh$ \quad:\quad\Cosh \qquadHyperbolic Cosine $\Coth$ \quad:\quad\Coth \qquadHyperbolic Cotangent $\csch$ \quad:\quad\csch \qquadHyperbolic Cosecant $\Csch$ \quad:\quad\Csch \qquadHyperbolic Cosecant $\curl$ \quad:\quad\curl \qquadCurl Operator $\DD$ \quad:\quad\DD \qquadthat is: \mathcal D $\dfrac {\d x} {\d y}$ \quad:\quad\dfrac {\d x} {\d y} \qquadRoman \d for Derivatives $30 \degrees$ \quad:\quad30 \degrees \qquadDegrees of Arc $\Dic n$ \quad:\quad\Dic n \qquadDicyclic Group $\DiscreteUniform {n}$ \quad:\quad\DiscreteUniform {n} \qquadDiscrete Uniform Distribution $a \divides b$ \quad:\quada \divides b \qquadDivisibility $\Dom {f}$ \quad:\quad\Dom {f} \qquadDomain of Mapping $\dr {a}$ \quad:\quad\dr {a} \qquadDigital Root $\E$ \quad:\quad\E \qquadEuler's number $\EE$ \quad:\quad\EE \qquadthat is: \mathcal E $\Ei$ \quad:\quad\Ei \qquadExponential Integral Function $\empty$ \quad:\quad\empty \qquadEmpty Set $\eqclass {x} {\mathcal R}$ \quad:\quad\eqclass {x} {\mathcal R} \qquadEquivalence Class $\erf$ \quad:\quad\erf \qquadError Function $\erfc$ \quad:\quad\erfc \qquadComplementary Error Function $\expect {X}$ \quad:\quad\expect {X} \qquadExpectation $\Exponential {\beta}$ \quad:\quad\Exponential {\beta} \qquadExponential Distribution $\F$ \quad:\quad\F \qquadFalse $30 \fahr$ \quad:\quad30 \fahr \qquadDegrees Fahrenheit $\family {S_i}$ \quad:\quad\family {S_i} \qquadIndexed Family $\FF$ \quad:\quad\FF \qquadthat is: \mathcal F $\Fix {\pi}$ \quad:\quad\Fix {\pi} \qquadSet of Fixed Elements $\floor {11.98}$ \quad:\quad\floor {11.98} \qquadFloor Function $\fractpart {x}$ \quad:\quad\fractpart {x} \qquadFractional Part $\Frob {R}$ \quad:\quad\Frob {R} \qquadFrobenius Endomorphism $\Gal {S}$ \quad:\quad\Gal {S} \qquadGalois Group $\Gaussian {\mu} {\sigma^2}$ \quad:\quad\Gaussian {\mu} {\sigma^2} \qquadGaussian Distribution $\gen {S}$ \quad:\quad\gen {S} \qquadGenerator $\Geometric {p}$ \quad:\quad\Geometric {p} \qquadGeometric Distribution $\GF$ \quad:\quad\GF \qquadGalois Field $\GG$ \quad:\quad\GG \qquadthat is: \mathcal G $\GL {n, \R}$ \quad:\quad\GL {n, \R} \qquadGeneral Linear Group $\grad {p}$ \quad:\quad\grad {p} \qquadGradient $\hav \theta$ \quad:\quad\hav \theta \qquadHaversine $\hcf$ \quad:\quad\hcf \qquadHighest Common Factor $\H$ \quad:\quad\H \qquadSet of Quaternions $\HH$ \quad:\quad\HH \qquadHilbert Space $\hointl {a} {b}$ \quad:\quad\hointl {a} {b} \qquadLeft Half-Open Interval $\hointr {a} {b}$ \quad:\quad\hointr {a} {b} \qquadRight Half-Open Interval $\ideal {a}$ \quad:\quad\ideal {a} \qquadIdeal of Ring $\II$ \quad:\quad\II \qquadthat is: \mathcal I $\map \Im z$ \quad:\quad\map \Im z \qquadImaginary Part $\Img {f}$ \quad:\quad\Img {f} \qquadImage of Mapping $\index {G} {H}$ \quad:\quad\index {G} {H} \qquadIndex of Subgroup $\inj$ \quad:\quad\inj \qquadCanonical Injection $\Inn {S}$ \quad:\quad\Inn {S} \qquadGroup of Inner Automorphisms $\innerprod {x} {y}$ \quad:\quad\innerprod {x} {y} \qquadInner Product $\intlimits {\dfrac {\map f s} s} {s \mathop = 1} {s \mathop = a}$ \quad:\quad\intlimits {\dfrac {\map f s} s} {s \mathop = 1} {s \mathop = a} \qquadLimits of Integration $\invlaptrans {F}$ \quad:\quad\invlaptrans {F} \qquadInverse Laplace Transform $\JJ$ \quad:\quad\JJ \qquadthat is: \mathcal J $\KK$ \quad:\quad\KK \qquadthat is: \mathcal K $\laptrans {f}$ \quad:\quad\laptrans {f} \qquadLaplace Transform $\lcm \set {x, y, z}$ \quad:\quad\lcm \set {x, y, z} \qquadLowest Common Multiple $\leadstoandfrom$ \quad:\quad\leadstoandfrom $\len {AB}$ \quad:\quad\len {AB} \qquadLength Function: various $\LL$ \quad:\quad\LL \qquadthat is: \mathcal L $\Ln$ \quad:\quad\Ln \qquadPrincipal Branch of Complex Natural Logarithm $\Log$ \quad:\quad\Log \qquadPrincipal Branch of Complex Natural Logarithm $\map {f} {x}$ \quad:\quad\map {f} {x} \qquadMapping or Function $\MM$ \quad:\quad\MM \qquadthat is: \mathcal M $\Mult$ \quad:\quad\Mult \qquadMultiplication as a Primitive Recursive Function‎ $\NegativeBinomial {n} {p}$ \quad:\quad\NegativeBinomial {n} {p} \qquadNegative Binomial Distribution $\Nil {R}$ \quad:\quad\Nil {R} \qquadNilradical of Ring $\NN$ \quad:\quad\NN \qquadthat is: \mathcal N $\norm {z^2}$ \quad:\quad\norm {z^2} \qquadNorm $\O$ \quad:\quad\O \qquadEmpty Set $\OO$ \quad:\quad\OO \qquadthat is: \mathcal O $\On$ \quad:\quad\On \qquadOrdinal Class $\openint {a} {b}$ \quad:\quad\openint {a} {b} \qquadOpen Interval $\Orb S$ \quad:\quad\Orb S \qquadOrbit $\Ord {S}$ \quad:\quad\Ord {S} \qquad$$S$ is an Ordinal $\order {G}$ $\quad:\quad$\order {G} $\qquad$Order of Structure, and so on $\Out {G}$ $\quad:\quad$\Out {G} $\qquad$Group of Outer Automorphisms $\paren {a + b + c}$ $\quad:\quad$\paren {a + b + c} $\qquad$Parenthesis $\Poisson {\lambda}$ $\quad:\quad$\Poisson {\lambda} $\qquad$Poisson Distribution $\polar {r, \theta}$ $\quad:\quad$\polar {r, \theta} $\qquad$Polar Form of Complex Number $\powerset {S}$ $\quad:\quad$\powerset {S} $\qquad$Power Set $\PP$ $\quad:\quad$\PP $\qquad$that is: \mathcal P $\Preimg {f}$ $\quad:\quad$\Preimg {f} $\qquad$Preimage of Mapping $\pr_j \paren {F}$ $\quad:\quad$\pr_j \paren {F} $\qquad$Projection $\PV$ $\quad:\quad$\PV $\qquad$Cauchy Principal Value $\QQ$ $\quad:\quad$\QQ $\qquad$that is: \mathcal Q $\radians$ $\quad:\quad$\radians $\qquad$Radian $\displaystyle \int \map f x \rd x$ $\quad:\quad$\displaystyle \int \map f x \rd x $\qquad$Roman $\d$ for use in Integrals $\rD$ $\quad:\quad$\rD $\qquad$Differential Operator $y \rdelta x$ $\quad:\quad$y \rdelta x $\qquad$$\delta$ operator for use in sums $\map \Re z$ $\quad:\quad$\map \Re z $\qquad$Real Part $\relcomp {S} {A}$ $\quad:\quad$\relcomp {S} {A} $\qquad$Relative Complement $\rem$ $\quad:\quad$\rem $\qquad$Remainder $\Res {f} {z_0}$ $\quad:\quad$\Res {f} {z_0} $\qquad$Residue $\Rng {f}$ $\quad:\quad$\Rng {f} $\qquad$Range of Mapping $\RR$ $\quad:\quad$\RR $\qquad$that is: \mathcal R $\sech$ $\quad:\quad$\sech $\qquad$Hyperbolic Secant $\Sech$ $\quad:\quad$\Sech $\qquad$Hyperbolic Secant $\sequence {a_n}$ $\quad:\quad$\sequence {a_n} $\qquad$Sequence $\set {a, b, c}$ $\quad:\quad$\set {a, b, c} $\qquad$Conventional set notation $\ShiftedGeometric {p}$ $\quad:\quad$\ShiftedGeometric {p} $\qquad$Shifted Geometric Distribution $\Si$ $\quad:\quad$\Si $\qquad$Sine Integral Function $\Sinh$ $\quad:\quad$\Sinh $\qquad$Hyperbolic Sine $\size {x}$ $\quad:\quad$\size {x} $\qquad$Absolute Value, and so on $\SL {n, \R}$ $\quad:\quad$\SL {n, \R} $\qquad$Special Linear Group $\Spec {R}$ $\quad:\quad$\Spec {R} $\qquad$Spectrum of Ring $\sqbrk {a}$ $\quad:\quad$\sqbrk {a}  $\SS$ $\quad:\quad$\SS $\qquad$that is: \mathcal S $\Stab x$ $\quad:\quad$\Stab x $\qquad$Stabilizer $\stratgame {N} {A_i} {\succsim_i}$ $\quad:\quad$\stratgame {N} {A_i} {\succsim_i} $\qquad$Strategic Game $\struct {G, \circ}$ $\quad:\quad$\struct {G, \circ} $\qquad$Algebraic Structure $\StudentT {k}$ $\quad:\quad$\StudentT {k} $\qquad$Student's t-Distribution $\SU {n}$ $\quad:\quad$\SU {n} $\qquad$Unimodular Unitary Group $\Succ$ $\quad:\quad$\Succ $\qquad$Successor Function $\Syl {p} {N}$ $\quad:\quad$\Syl {p} {N} $\qquad$Sylow $p$-Subgroup $\T$ $\quad:\quad$\T $\qquad$True $\Tanh$ $\quad:\quad$\Tanh $\qquad$Hyperbolic Tangent $\tr$ $\quad:\quad$\tr $\qquad$Trace $\TT$ $\quad:\quad$\TT $\qquad$that is: \mathcal T $\tuple {a, b, c}$ $\quad:\quad$\tuple {a, b, c} $\qquad$Ordered Tuple $\UU$ $\quad:\quad$\UU $\qquad$that is: \mathcal U $\var {X}$ $\quad:\quad$\var {X} $\qquad$Variance $\vers \theta$ $\quad:\quad$\vers \theta $\qquad$Versed Sine $\VV$ $\quad:\quad$\VV $\qquad$that is: \mathcal V $\WW$ $\quad:\quad$\WW $\qquad$that is: \mathcal W $\XX$ $\quad:\quad$\XX $\qquad$that is: \mathcal X $\YY$ $\quad:\quad$\YY $\qquad$that is: \mathcal Y $\ZZ$ $\quad:\quad$\ZZ $\qquad$that is: \mathcal Z

Others may happen as and when I think of them. --prime mover (talk) 03:48, 25 August 2018 (EDT)

This is awesome! Thanks!! — Timwi (talk) 19:27, 27 August 2018 (EDT)

## Refactoring of Combination Rules for Sequences

As you may have noticed, work is in progress refactoring the Combination Theorem for Sequences section.

This is ongoing, and in the meantime the pages will look a mess and links will be broken.

Please bear with me, this is being fitted in around a change to my work schedule in which I have been told I am now contracted to work an extra hour a day, so I have one less hour in the mornings to do this stuff. Apologies. --prime mover (talk) 02:24, 4 September 2018 (EDT)

## Breaking news

Riemann hypothesis likely remains unsolved despite claimed proof -- Timwi (talk) 12:10, 28 September 2018 (EDT)

## Proofs Wanted category

So... I realize it is a tad late for this suggestion, but would it perhaps be a good idea to have separate proofs wanted (sub)categories for analysis, algebra, probability theory, discrete maths, chess, ...? The category currently contains 1700 pages and this is sure to grow even more over time. Even if we don't go back and categorize all these 1700 pages more carefully, it could help if we did this for future pages, so that new collaborators can more easily find proofs that are wanted in their area of interest. KarlFrei (talk) 04:40, 27 September 2018 (EDT)

Unfortunately the "Proofs Wanted" category is added automatically by the ProofWanted template, and to subcategorise these would require some work. I'm not saying it won't happen, but it would have to wait till someone has enough headspace.
In the meantime feel free to browse around the "Maintenance Needed" category to see if there is anything there you might like to get involved in. There are several categories, some of which are more intellectually accessible than others. --prime mover (talk) 06:02, 27 September 2018 (EDT)

## Bots?

It occurs to me that it would be useful to have bots. For instance, a bot to replace a matching pair of left and right parentheses by the paren command. Has there been any work done in this direction? KarlFrei (talk) 11:28, 4 October 2018 (EDT)

Not so far.
It would be useful, but then contributors have not always adhered to a standard code style. Some have insisted on using their own preferred style, and some have even pathologically refused to write in any consistent sort of style at all. So programming it to find the edge cases may be challenging. --prime mover (talk) 11:34, 4 October 2018 (EDT)
I would first have to figure out how to program bots at all... Still, this could be fun. KarlFrei (talk) 06:53, 5 October 2018 (EDT)
I have been looking into this, even managed to get beyond the initial setup (key word: pywikibot). I do agree with PM that it will be hard to identify the use cases. More so since parentheses are among the most overloaded symbols in mathematics (denoting sequences, ideals, modulo classes, equation numbering, ...).
Since we are moving in a direction of semantics, it will unfortunately come down to tough hand work. What we can possibly do, is establish certain wishes that help us to clean up the site.
Subsequently I, or other people, might be able to program out the relevant bots and make them work. Running them is another matter entirely of course.
In this direction I am concretely thinking about e.g. an overview of headings used (and on which pages), subpage structure, categories which do not conform to established template usage... the list goes on. The benefit of such lists is that the human mind is good at doing the same thing repeatedly, more so than doing different things each second. So even when we cannot automate the resolution, it might be possible to streamline the efforts. I would be interested in taking this discussion further. As a start, let's make a list of what could possibly be beneficial (so disregarding any feasibility concerns; the proof writer bot is welcomed ;) ). — Lord_Farin (talk) 05:35, 7 October 2018 (EDT)
Further to LF's comment: "we are moving in a direction of semantics" -- some progress is being made with the various usages of $\paren \cdot$, for example:
\struct for "structure", e.g. Algebraic Structure, Topology etc.
\tuple for "ordered pair, ordered tuple"
and of course \paren for general parenthesised entries.
But this does not go as far yet as I would like. Still in mind is \funct f x for $f \paren x$, and I would love to think up a sufficiently compact key for replacing \paren {-1}^n, so any suggestions there are welcome.
Similar for the various usages of $\left\langle {\cdot}\right\rangle$. But the various usages of $\sqbrk \cdot$ are not so easy to name and identify.
Advice and suggestions all welcome. --prime mover (talk) 06:05, 7 October 2018 (EDT)

I would like to err on the side of caution in these matters. There is a danger of PW becoming idiosyncratic, only speaking its own dialect. I don't think we are there at this moment, but things like \funct f x would bring the danger closer.

Concretely I would like to suggest that we stick to the low-hanging fruit (equivalence classes and interval notation come to mind, as do parentheses given our house style convention). My .guess is that there is plenty of low-hanging fruit. Bots could potentially help us in applying some of the improvements, but this has to be investigated on an individual basis. — Lord_Farin (talk) 14:09, 7 October 2018 (EDT)

Okay I take your point ... is idiosyncratic inherently bad, though? I have started experimenting with \map f x for $\map f x$ which I find does make reading a page's $\LaTeX$ easier to follow. But I can reverse these out if you think it's too far.
Other low hanging fruit: the various constructs with \operatorname are the main ones I'm looking at. --prime mover (talk) 17:46, 7 October 2018 (EDT)
Address \operatorname calls sounds great. To your important point: I agree that idiosyncrasy has its place and can be outweighed by other benefits (such as legibility and maintainability), see also our heavy usage of templates. However in the case of \map I'm not so convinced somehow. At least not at this moment. Maybe because the construct $f(x)$ is so prevalent also when $f$ is not really a map (functional, measure, propositional function, operator, you name it) and this can easily lead to the construct being used in non-semantic ways (also strictly speaking $f(x)$ is the "application of the mapping $f$ to the element $x$", which "map" can be argued to not convey sufficiently). But as I said, I can totally imagine that over time my position will change. — Lord_Farin (talk) 12:57, 8 October 2018 (EDT)

## Users

I know, this is not particularly urgent or important... I guess I like cleaning up.

The user list at Special:ListUsers contains 3456 users (!), but the vast majority of these are accounts with zero activity. I realize that there is a separate Active users list, but still, maybe accounts with zero contributions that are more than, say, two years old could just be deleted? This is just junk which is cluttering the list.

Alternatively, it would perhaps be possible to modify the software so that only users with at least one edit are shown on the list of users. KarlFrei (talk) 07:00, 5 October 2018 (EDT)

If my account were suddenly deleted for no reason other than having made no edits in 2 years, I’d be furious and I’d probably never contribute again. I’m worried that you’re even entertaining the thought. What you should entertain instead if you find the list unhelpful, is automatically filtering the list, not to delete accounts of users who aren’t doing anything wrong. — Timwi (talk) 15:39, 5 October 2018 (EDT)
I have never advocated deleting accounts (except, as I say, for those of some obvious spam-attacks we had some time ago). Your contributions have been valued.
But there is an outstanding question: why would anyone want to spend time scanning through the list of user accounts in the first place? What does a person get out of it?
(Why did you delete my post, BTW?) --prime mover (talk) 16:10, 5 October 2018 (EDT)
That was not intentional, I do apologize. It must have been a conflict from editing the page at the same time. I only meant to post the above message, which was in response to KarlFrei. I will restore the messages I accidentally deleted below. — Timwi (talk) 21:06, 5 October 2018 (EDT)
No worries. These things do happen, I gather -- but never understood how. The timestamps don't eve match! --prime mover (talk) 04:12, 6 October 2018 (EDT)
I am sorry, I did not mean to upset anybody. I think that there has perhaps been a misunderstanding. I never suggested to delete accounts that were temporarily inactive. I only suggested to delete accounts that never contributed anything at all AND were more than two years old. It was only an idea for a minor cleanup, which I thought should be relatively uncontroversial. As I wrote right at the start, it is not particularly important or urgent. KarlFrei (talk) 08:45, 6 October 2018 (EDT)
Never mind, I just spotted the checkbox. Still, my view is that these accounts should just be deleted. KarlFrei (talk) 07:07, 5 October 2018 (EDT)
There are a number of contributors who contribute but rarely. More than once has a contributor who has not been seen for years sprung back to life and started contributing once more. We have no intention of deleting any accounts (except perhaps we could weed out some of the blocked accounts of the spammers who plagued us for a while). As far as I know, the response of the website is not adversely affected by the fact of there being a large number of accounts. --prime mover (talk) 07:15, 5 October 2018 (EDT)

Speaking of cleaning up, it is probably time to archive this page again. KarlFrei (talk) 07:12, 5 October 2018 (EDT)

## Rules

(continuing the discussion from my user page)

Thank you very much for your responses. Allow me to make a few points.

1. I am all in favour of having different proofs for the same result on this website. Indeed, I started off by adding some alternative proofs myself! It is part of the beauty of mathematics that many things can be proven in completely different ways.
2. It would be fantastic if we could indeed have a reasonable discussion about how much alteration of proofs can be allowed. I was honestly getting the impression that the allowed amount of alteration is zero (apart from bringing it into house style etc.) and furthermore that this is not open to discussion.
3. As to why I want to change some proofs: I want to make them more beautiful. If I can only achieve this by having the nice proof side by side with the ugly version, then this seems rather pointless. Moreover, it potentially leads to a situation where we end up having 10 or 20 different proofs of the same result that each only differ in one or two steps.
4. From now on, I will add maintenance tags to any new pages that I create, and hope that that will be sufficient. I will stick to the house style (rules) that I can remember but I am not going to memorize all of them.
5. Even though I formulated my list of house rules in a rather sarcastic manner, I do believe it would be a giant improvement if we pointed these out (written in a more neutral tone of course) to new editors. Lord_Farin himself wrote that this was a familiar pattern for new versus old users. If the new users could at least be pointed to prior discussions on the same topic, or just plain informed about the secret rules BEFORE they break them, I believe this could save a lot of frustration as well as hopefully avoid repetitive discussions.
6. At the very least, the help pages should be expanded. In my view, there should be nothing about this website that an editor could not find out by reading the appropriate help pages. For instance a brief section about Notes and why they are discouraged. The policy makes sense, so why hide it? There are by now 10 years of discussions on these pages and contributors cannot be expected to read all of that.
7. Shouldn't authorship of pages be irrelevant on a wiki?

Let me conclude by saying that I think this is a fantastic website and I believe it can really help people understand proofs, as every step can ideally be clicked on and further explained. This is a structure which cannot be achieved in books at all (well, you would have to do a LOT of page turning...) and one which I expect students would love. (I cannot test this hypothesis myself as I am not in an English speaking country.) I am also very impressed by the huge amount of work that has been put into this site already.

You're in the minority. The general consensus of opinion is that this site is appallingly bad, and should not exist. --prime mover (talk) 03:21, 12 October 2018 (EDT)
You've told me this before :-) Recall however that you could not find any sources for this claim the last time! I am not so sure that I am in the minority. KarlFrei (talk) 03:29, 12 October 2018 (EDT)
Minority of one. --prime mover (talk) 03:55, 12 October 2018 (EDT)

For me, the main goal of contributing here is for the benefit of humans, as well as satisfying my desire for beauty. (However, the website appears to also have some secret goals as well as secret rules, but that is a topic for another day.) KarlFrei (talk) 03:07, 12 October 2018 (EDT)

What we are experiencing here is frustration expressed by a new contributor who is disappointed that things aren't what he wants them to be. --prime mover (talk) 04:51, 13 October 2018 (EDT)
Ad 2: I think this would be good. I wonder if there is anything that can be meaningfully said to it, though... Maybe a discussion on individual basis is always required, and more efficient than trying to come up with some formulation that will not entirely capture "the policy".
A proof as presented is often as it appears (or isomorphic to how it appears) in a particular source work. A major restructuring of such a proof is undesirable because then what is on the page no longer matches the source work cited on that page. Minor tinkering with the presentation is fine; again we have a house style which we prefer to stick to, for example: "$A$ therefore $B$ (because of result $C$)" is suboptimal, we prefer the form "We have $A$. "From result $C$ it follows that $B$". Once we have arranged the proof into that form, there is little "improvement" that can be done which does not constitute a rewrite. And a rewrite, I contend, is to be added as a separate page.
Bottom line is: unless you are bringing the style up to scratch, you should not need to be amending proofs that are already there. --prime mover (talk) 04:51, 13 October 2018 (EDT)
Yes, you have mentioned this before, and this (the last line in particular) is what I have now written into the help pages. The first paragraph is another point that could/should definitely be mentioned [[1]]. Please do this as I can no longer edit that page. I think it would help avoid confusion in the future.
I am still trying to understand the reasoning behind this policy. (It is important for me to understand things.) Why do we stick so closely to source works? Is it just because you like it that way? I have seen you do this with a proof from a book that you really hated at one point, and I do not understand this seemingly undue deference to apparently low quality sources. KarlFrei (talk) 05:30, 13 October 2018 (EDT)
Ad 4: This will indeed suffice :).
You should not need to add maintenance tags. This is usually done by someone coming after you who is in a position to inspect the code and add the tags as necessary. Yes, there are people who (soon after starting to contribute here) have been producing pages which adhere to house style practically right from the start. If you feel unable to do this, or are unwilling to do this, then yes, feel free to add whatever tags you consider may be necessary -- although if you have already identified non-compliances on the pages you generate, why not address these matters yourself? --prime mover (talk) 04:51, 13 October 2018 (EDT)
Ad 5/6: It would be great if you could suggest specific improvements/expansions (as you have already started to do). Maybe entire new pages need to be written.
I am glad that you liked my changes to the help pages. KarlFrei (talk) 05:30, 13 October 2018 (EDT)
On the other hand, the pages are already large enough to be unwieldy. It would be hoped that by becoming familiar with the site (by using it, and by finding out what is already there), one can get a good idea of the general intent of what we are doing here. If a contributor has a completely different idea of what he or she thinks this site should be, that is a completely different discussion. But (purely as a point of good manners) one should at least make an attempt to work within the given framework.
Maybe we can relegate other material to different pages and focus on the main points. Maybe we should limit the first paragraph to mentioning exactly this ("Just walk along, see what we do. For specific guidelines, see below."). Maybe we can identify some articles that express this in a good way. Seeing the pattern of misunderstanding, we might consider a change to make the expectation more explicit. (NB. Obviously I am not advocating that anyone can just do whatever they want, but instead that we could experiment to find out if we can do a better way of communicating what the way of working is.) — Lord_Farin (talk) 06:27, 13 October 2018 (EDT)
That sounds like a good idea. Perhaps we should have started with this. Never anticipated we'd ever have trouble of this sort of magnitude. --prime mover (talk) 11:10, 13 October 2018 (EDT)
Ad 7: It is my opinion that structural, comprehensible exposition of mathematical content requires some deeper ideas and in some sense, a plan. If the author of the "plan" is around, why not ask? If the content is already there, why not outline and discuss the new plan somewhere? (Of course this only applies to "material changes"; but see 2. above). — Lord_Farin (talk) 04:05, 13 October 2018 (EDT)

## 16000

Congratulations to all on reaching a nice round number of proofs again! Now, on to the next proof... KarlFrei (talk) 06:05, 13 October 2018 (EDT)

Most of those are probably redirects or aggregation pages, or notes pages. Very few of them are actually proofs as such. --prime mover (talk) 18:40, 13 October 2018 (EDT)

## Suggested change in approach to section spacing

All, I've been following up on an old idea to simplify section spacing. Concretely, to eliminate the need to have multiple whitelines in a page's source to achieve the desired spacing.

Concretely, it involves the following steps:

1. As seen on User:Lord_Farin/common.css, the section spacing for H2 headings (except the first one) has been increased to 2.5em, which is 1.5em more than it presently is. I arrived at this number by a visual experiment. I've tried various levels of zoom and the effect is consistently the same as having an extra white line in the source code.
2. To correct the existing white lines (avoiding double whitespace), there is a tiny bit of JavaScript User:Lord_Farin/common.js. It removes empty paragraphs before H2 headings (i.e. those created by double white lines in the source code).
3. To fix the issue structurally (so that we do not need the JS to do work every time a page is loaded), I have created a script for the experimental bot that I have been configuring. The effect has been demonstrated in the following edit: User:Lord_Farin/Bot.

To demonstrate the effect of step 1. compared to the existing practice, you can use User:Lord_Farin/Sandbox, and the "inspect element" functionality of your browser (F12 usually) to adjust the spacing of the left heading to 2.5em.

For me, the effect of 1. + 2. is that both samples look completely identical.

With the aid of the bot described in 3., we can start applying 1. to all existing pages in an automated fashion (additionally giving a proof of concept fur further automation).

What are your thoughts? — Lord_Farin (talk) 10:03, 14 October 2018 (EDT)

NB. To minimise impact, the current changes to CSS and JS only apply to user space. I will take care of adjusting this before moving them over to their MediaWiki counterparts. NB2. I have checked and in last months' reports I could not find browser sessions which didn't support the technology involved in this adjustment, so from that perspective we are also fine.

Quick thoughts ...
a) Why not H3 headings too?
b) We have a style that evolved wherein the equivalence proofs resulted in multiple definitions not being presented with the same gap as on the Definition page itself.
No other things come to mind. --prime mover (talk) 16:17, 14 October 2018 (EDT)
Two birds, one stone: Because the definitions in b) are transcluded using H3 headings. — Lord_Farin (talk) 16:25, 14 October 2018 (EDT)
This plan sounds great! Go for it, I would say. (Perhaps let the bot run for only 10 seconds or so first, to see what it does.) Any kind of automation that we can build in is great. Next on my personal wishlist would be automated linking of definitions (only for uniquely defined concepts of course). KarlFrei (talk) 09:25, 22 October 2018 (EDT)
Incidentally, Wikipedia has a bot which automatically signs unsigned posts on talk pages (SignBot?). We may want to start using that as well (if we can just copy it over). KarlFrei (talk) 09:27, 22 October 2018 (EDT)

## Theorem of Applied Group Theory

Have you noticed that when you go through a door (with a traditional "rotary" lock on it), unlocking it to go through and then locking it again when you've passed through), you turn the key in the same direction both times?

I mentioned this fact on my facebook page and I had a number of people replying that I am incorrect.

I believe this can be modelled as an application of group theory.

Should this fact also be added to the Veridical Paradoxes category? --prime mover (talk) 07:01, 4 November 2018 (EST)

You are definitely right. It hasn't struck me as paradoxical, though. But maybe that's just me. — Lord_Farin (talk) 14:27, 5 November 2018 (EST)

## Help needed with Subset Products of Normal Subgroup with Normal Subgroup of Subgroup

Anyone with a good level of skill in group theory who can finish off (or completely rewrite) the above proof?

I can't work out how to prove that if $H$ is a subgroup of $G$, and $N$ is normal in $G$, and $K$ is normal in $H$, then $NK$ is normal in $NH$. I seem to need to prove that $K$ is normal in $N$ which is not where I wanted to go. Anyone? --prime mover (talk) 08:06, 5 November 2018 (EST)

The solution is to note that $K \le G$, and then use $g N = N g$ from $N \lhd G$ to infer $K N = N K$. I've completed the proof using this approach. — Lord_Farin (talk) 14:45, 5 November 2018 (EST)
!?! Looked right past it. Good job. --prime mover (talk) 15:03, 5 November 2018 (EST)

## Possible error in Inverse Hyperbolic Sine is Odd Function

Hello! I am new and hope that this is the right place to ask. The Help:Editing page discourages editing existing proofs as a newbie. But as regards Inverse Hyperbolic Sine is Odd Function, I think that the last line of the proof is wrong. It should instead be: $y = - \sinh^{-1} x$. Can I modify it this way?

Feel free. I removed the offending section of Help:Editing, which was unsanctioned.
You are correct -- there is indeed a silly mistake on the page in question. --prime mover (talk) 13:26, 24 November 2018 (EST)
Thank you so much.

== How to avoid plagiarism while obeying Help:Editing/House Style/Sources

The inspiration for a proof I wrote came from an online source not listed in Help:Editing/House Style/Sources. I wrote the proof. I filled in all the details and organized the order of statements. But once I saw the concepts mentioned in the online source, it was all obvious, just a matter of detail work. How do I obey the citation policy without plagiarism? I am told that in academic work one must always reveal the source of ones ideas. Can I reveal where I got the ideas without making a "general citation source"? Thank you --Pelliott (talk) 22:25, 25 January 2019 (EST)

## How to avoid plagiarism while obeying Help:Editing/House Style/Sources

I got the inspiration for a proof from a online source not mentioned in Help:Editing/House Style/Sources. I wrote the proof. I filled in all the details and ordered all the statements. But it was all obvious once I saw the concepts mentioned together in my online source, just detail work. I am told that in academic work, one must always reveal all the sources for one's ideas. How can I do this? Can I reveal where I got the idea without making a "general citation source"? Thank You --Pelliott (talk) 22:38, 25 January 2019 (EST)

Is this an academic work? I never thought so. It's just an amateur web page. --prime mover (talk) 05:21, 26 January 2019 (EST)

## Things that are missing or hard to find.

This is a list of things that are missing or hard to find. Pythagorean Identity it's there somewhere but hard to find. Proof that reals are uniquely embedded in complexes as a normed field. Slope-intercept form of equation of straight line. Two-point form of equation of straight line. I will add to list as I find more. --Pelliott (talk) 16:03, 2 February 2019 (EST)

## Account request

Can we remove the word length constraint on the account request biog? I get the feeling that prospective contributors consider 50 words is a bit of an imposition. I would be tempted to agree with them, I'm afraid.

All account requests need moderator approval, and it should be no problem for one such moderator to actually make a judgment call as to whether the request is genuine. And if the occasional robot spammer gets through, well, no lasting harm will be done as long as at least one contributor is borderline vigilant. --prime mover (talk) 03:02, 11 March 2019 (EDT)

Sure, I'll change it to be 1. --Joe (talk) 11:19, 11 March 2019 (EDT)
I think now we're in the sweet spot. --prime mover (talk) 02:49, 12 March 2019 (EDT)

## There is a typo at the page https://proofwiki.org/wiki/Image_of_Union_under_Mapping

The last line of proof 1 states "$𝑓[𝐴]∪𝑓[𝐵] \subseteq 𝑓[𝐴∪𝐵]$ by the Definition of Set Equality". '$\subseteq$' should be '='.

I tried to correct the typo, but didn't know how. Please update the page. Thanks.

Done.
You are encouraged to learn how MediaWiki works. --prime mover (talk) 14:40, 29 March 2019 (EDT)

## Using theorems within definitions

Coming around to defining excess kurtosis, which is the difference between a distribution's kurtosis and that of the normal distribution. ($3$) As the definition hinges on this fact and appears unmotivated without it, I'm wondering how to introduce it. Thinking of doing it by, for example "Excess kurtosis is the difference between the kurtosis of $X$ and the normal distribution. So, by, Kurtosis of Normal Distribution...", but I'm not sure if this is the usual thing to do. Caliburn (talk) 05:16, 5 April 2019 (EDT)

What we have done in the case of some of the stuff in abstract algebra is have a definition: "The ring of (whatever)" and then in the Also see section, have the link to the proof page "Ring of (whatever) is a Ring".
Same could be done for kurtosis. "Kurtosis is a measure of how fat the tails are" (or however you want to word it) and is the this divided by the that. No theorem needed at that stage, but then all the backup proofs appear in also see. --prime mover (talk) 08:11, 5 April 2019 (EDT)
"Excess kurtosis is the kurtosis with that of the normal distribution subtracted from it: $k - k_{norm}$" or whatever the notaiton is. --prime mover (talk) 08:16, 5 April 2019 (EDT)
But doing it that way wouldn't we have to quote Kurtosis of Normal Distribution in pages about excess kurtosis? My thought was to pack that in to the definition page by quoting the kurtosis of the normal distribution there, and was wondering where I could do that. Caliburn (talk) 11:04, 6 April 2019 (EDT)
Nope, sorry, I don't understand the question. Anyone else care to have a go? --prime mover (talk) 17:48, 6 April 2019 (EDT)
Sorry, probably not being clear enough. I was asking if it would be find to use, say something like "Excess kurtosis is the difference between the kurtosis of $X$, $\alpha_4$ and the normal distribution. By Kurtosis of Normal Distribution, this is given by $\alpha_4 - 3$. Caliburn (talk) 18:05, 6 April 2019 (EDT)
Feel free to put such a page together and see how it works. We can always move things around if we don't like how it flows. --prime mover (talk) 03:18, 9 April 2019 (EDT)

## Ordered Integral Domains and all that

I am currently working on tidying up and rationalising the work around the definition and properties of the Definition:Ordered Integral Domain.

As can be seen, I have decided to rename the positivity property (as it is defined in 1969: C.R.J. Clapham: Introduction to Abstract Algebra) to the Definition:Strict Positivity Property, which is a name for this that I have not come across in the context of integral domains (although for example in measure theory it is indeed a thing) in order to distinguish it from the Definition:Positivity Property that can be defined on a general ring, as defined in 1965: Seth Warner: Modern Algebra.

It's a bit of a mess at the moment while I tidy up some loose ends where the current definitions have got a bit confused with each other. As it is not immediately clear without a lot of work exactly which abstract algebraic entities can be reliably defined to support which properties, I am going to follow 1969: C.R.J. Clapham: Introduction to Abstract Algebra for the Definition:Strict Positivity Property and apply the latter construct to the Definition:Integral Domain only, while the Definition:Positivity Property is allowed by 1965: Seth Warner: Modern Algebra to apply to a general Definition:Ring (Abstract Algebra) (and in fact is defined secondarily to the concept of the Definition:Ordered Ring).

Please excuse the various incidences of backtracking and deleting -- I think I know where I'm going now, and I will try to get this resolved over the next few days. --prime mover (talk) 03:53, 14 April 2019 (EDT)

That seems to have worked out all right. Now I move on to my next subproject. --prime mover (talk) 01:57, 16 April 2019 (EDT)

## Principle of Mathematical Induction and all that

Having completed chapter $2$ in Clapham concerning Definition:Well-Ordered Integral Domains, I move on to to chapter $3$, where he attacks the Principle of Mathematical Induction. There are a number of approaches to this subject in the literature, all of which are equivalent, but all of which use different axiomatic frameworks to do it. I want to try and pull them all together into a coherent and modular whole. This may take some time and I will probably need to take it over a number of weeks.

Comments and advice from anyone directly concerned with this activity are welcome.

This may be interrupted by various periods of inactivity while I am going to find myself away from the keyboard for days at a time, so please bear with me. --prime mover (talk) 02:06, 16 April 2019 (EDT)

Didn't take as long as I thought it would. Definition:Mathematical Induction is the main fruit of that exercise. Time to move on. --prime mover (talk) 16:44, 18 April 2019 (EDT)

## Presentation standards

Is there any point trying to maintain standards of presentation and attempt to adhere to house style? Or shall we just copy and paste pages from wikipedia? Does anyone care either way? --prime mover (talk) 17:37, 9 June 2019 (EDT)

I'm not sure what you are trying to solicit from others with these questions. Here's my personal take on them.
I can't see why anyone is going to want to contribute to a website that has no standards of presentation or house rules, or is simply a cut and paste from wikipedia. I'm fine with the standards of presentation and house rules as they are. I think they contribute to the overall aims of the website. The standards evolve, and I adjust accordingly. There are plenty of things for me to sweat over, standards is not one of them.
Wikipedia and $\mathsf{Pr} \infty \mathsf{fWiki}$ seem to have different purposes. My experience is that Wikipedia is at best a starting point for an investigation of some mathematical topic. I expect and aim to make $\mathsf{Pr} \infty \mathsf{fWiki}$ an endpoint for any mathematical investigation. --Leigh.Samphier (talk) 19:11, 14 June 2019 (EDT)
Should we just delete such cut-and-pastes? Or just add maintenance tags all over them and hope someone will address the issues? It can be a horribly tedious task to tidy such pages up, especially if the page in question is on a topic that has not been addressed so far, and so none of the links go anywhere. --prime mover (talk) 19:23, 14 June 2019 (EDT)
Could the offending page be moved to the authors personal space, effectively "unpublishing" the page, and the author given the opportunity to bring it up to standard? I think this is acceptable for any page that falls way short of being acceptable. Maintenance tags could be added to the page to indicate the things that need to be corrected before moving the page. My experience is that pages that are well below being acceptable are the hardest pages to review and correct and generally require a rewrite from scratch. --Leigh.Samphier (talk) 20:33, 14 June 2019 (EDT)
If the offending page represents a liability to the website then it should be deleted --Leigh.Samphier (talk) 20:50, 14 June 2019 (EDT)
Sounds like a good plan. I will start implementing it. --prime mover (talk) 03:38, 15 June 2019 (EDT)

## Too long a proof?

I tried adding more content to https://proofwiki.org/wiki/Lerch%27s_theorem_(Inverse_Laplace_transform_uniqueness) in order to finish the proof but it would not appear. Did I go over some limit in page bytes?

no --prime mover (talk) 16:08, 17 June 2019 (EDT)
looks like something did get added (300+ bytes) but then immediately got deleted again. You must have done something wrong, like edited an old version. --prime mover (talk) 16:08, 17 June 2019 (EDT)
Incidentally, I trust you are planning to take some heed of house style? --prime mover (talk) 16:09, 17 June 2019 (EDT)
Try adding content and you will see that nothing shows up in preview or after saving changes. (See the line "Up to here it works. Here is content that is not showing up (I simply copy pasted the above align):")
Let's have some patience. Typing the proof alone is hard work in itself. Others are free to improve it.
Something funny going on. Leave it with me, I'll bring it up to house style.
One of the reasons for the stringent nature of our house style is to guarantee that the $\LaTeX$ is well-formatted, so that it renders on the page properly. I expect that the reason it won't show is because the $\LaTeX$ is invalid. Difficult to tell where, as it is it's impossible to comprehend. --prime mover (talk) 16:44, 17 June 2019 (EDT)
You will see now that it works. It shows all the code. But as soon as I add something, it dies on me.
Okay I will go read the latex house style more carefully to prevent problems like this.
There was a problem with the final begin-end equation. Don't know what, but note that this site does not support that construct well. We just use the dollar delimiters and put a colon in front. Everything gravitates to the left hand side of the page, which is consistent with the style rule which says short, simple sentences, one per line. --prime mover (talk) 17:34, 17 June 2019 (EDT)
It improved but it still doesn't work for me.
When I am done editing a post in sandbox mode, how do I move it out into a main page? I don't want it to redirect to me.
Get it complete first. As I say, you will need to change your constructs as I advised. Try putting bits of it in html comment delimiters, then they won't render and that way you can isolate the specific thing which causes it to fail. --prime mover (talk) 18:15, 17 June 2019 (EDT)
I followed the tips you mentioned (no equation env, no double parantheses or curly bracket). The align environment is much faster to type than the "eqn" template. Can we just go with that? With the eqn template it will take me triple the time to type that content.
I did check for errors that way but it doesn't help. For example, I didn't get any errors on "Show Preview" when using the equation environment but apparently it gave internal problems to proofwiki that didn't show in preview.
As I say, it's probably because of that "align" rubbish that we don't support. I'll take another look another day, but till then, you're welcome to carry on trying to work out what the problem is.
You've been given suggestions, which you are at liberty to take advantage of. If you choose not to, then please do not be surprised if further requests for help may take some time to be responded to. --prime mover (talk) 19:05, 17 June 2019 (EDT)
I will go do the change for align (even though it shows fine during preview).
For example, since the main issue is that the Wiki parser takes precedence, maybe ProofWiki can have a code-transfer program. For example, having a visual editor where we can code pieces of the code in Latex, but then automatically get translated into language that the Wiki parser is happy with.
Other contributors manage perfectly well. --prime mover (talk) 01:02, 18 June 2019 (EDT)
That doesn't negate the point that using the align environment is much faster.
Can you provide some metrics on that to prove that? But be that as it may, we prefer not to compromise quality for the sake of convenience. As such, we follow common industry software practices whereby standards are laid out and developers are required to stick to them. --prime mover (talk) 18:16, 18 June 2019 (EDT)
ProofWiki has to adapt to the users as well. They have to figure out a way so that we can just transfer our existing Latex code into some separate compiler that then does the job of translating into the wiki parser format, which apparently takes precedence over latex. For example, it will translate the align environment into eqn template.
All very well, but we insist that such code adheres to standards of presentation and structure. --prime mover (talk) 18:16, 18 June 2019 (EDT)
We are not writing code into wiki in our everyday lives.

## Chessboard capability

I have taken the liberty of finishing the work of setting up a chessboard template, which I took from Wikipedia. There is still room for further enhancements, but this will be a start.

See {{ChessDiagram}}. --prime mover (talk) 11:22, 24 June 2019 (EDT)

## A quick nomenclature question (denotes vs is)

I gather that saying, for example, "where $\Gamma$ denotes the gamma function" is preferable over "where $\Gamma$ is the gamma function". When should this rule generally be applied? Is "let $\map f x$ denote the something of $x$" preferable over "let $\map f x$ be the something of $x$"? Or is the distinction unimportant? Caliburn (talk) 17:26, 27 June 2019 (EDT)

Intuitive feel. Basically, when you are invoking a concept which is defined elsewhere and is referenced on a page where you need to use it, I would tend to use "denotes". "Let $\Gamma$ denote the Gamma function."
When you are specifying something which is "invented" for the page you are working on, it's "be" or "is". "Let $S$ be the set defined as: $S := \set {1, 2, 3}$."
So it's "Let $x$ be an integer" but "Let $\Z$ denote the set of integers."
That's how I like to do it, anyway. --prime mover (talk) 17:52, 27 June 2019 (EDT)
This makes sense, thanks. Caliburn (talk) 18:12, 27 June 2019 (EDT)
My use of ‘denotes’ is somewhat different and less defined. On reflection, I use ‘denotes’ to emphasise that the definition is unfamiliar/unexpected or unusual. I would use ‘denotes’ to introduce a concept not normally encountered in the current context. I would use ‘denotes’ to introduce a notation that is not the usual. The purpose is to bring attention to the definition.
I would also use ‘denotes’ in the case when I have used a notation before it has been defined, as in the case you have given ("where $\Gamma$ denotes the gamma function"). —Leigh.Samphier (talk) 07:30, 28 June 2019 (EDT)

## Automated checker for format and volunteer work

There are quite a few rules for formatting Proofwiki. To avoid having subjective arguments with others, I suggest creating some automated compiler that checks for format in our ProofWiki posts. For example, throwing an error when a line sentence contains more than 20 words or when the semicolon dollar sign is not followed by displaystyle. As more posts are getting added, it will become harder for the admins to keep track of all the changes and give useful concrete format suggestions. So there needs to be some automated format checker. --Tkojar (talk) 17:05, 2 July 2019 (EDT)

Also, I request that admins stop placing incomplete posts into user sandboxes. If a post has issues, then just place the appropriate labels like "needs to be formatted better". That way we can receive help from other more experienced volunteers. Otherwise, this is too much pressure for volunteers. --Tkojar (talk) 17:05, 2 July 2019 (EDT)

Posts which do not conform to house style will continue to be put into sandbox.
To put things in perspective, similar badly-styled and non-conformant pages entered into Wikipedia get deleted.
If you want your work to be in the mainstream of $\mathsf{Pr} \infty \mathsf{fWiki}$, you may wish to consider the option of familiarising yourself with house style and attempting to adhere to it. --prime mover (talk) 18:12, 2 July 2019 (EDT)
I agree with having some sandbox. Just don't put them in a user-based sandbox. We are only volunteers. If no other volunteer wants to improve on it, then let it get automatically deleted. --Tkojar (talk) 18:44, 2 July 2019 (EDT)
There are already categories such as "tidy articles" and "help needed". So just keep them there. Stop putting them under user-based sandbox.--Tkojar (talk) 18:44, 2 July 2019 (EDT)
If you want create a category called "very badly-style" posts and even put an expiration date on them. --Tkojar (talk) 19:20, 2 July 2019 (EDT)
As you point out, this site is edited by volunteers. And most of the contributors have no trouble with the house rules. They create pages which are by and large compliant with the rules, some more than others, and in most cases it takes only a few small adjustments to achieve the final perfectly formed page that gives $\mathsf{Pr} \infty \mathsf{fWiki}$ its character. And I can't imagine who would want to waste their time writing such a pointless tool to automatically reformat ugly and unreadable $\LaTeX$ written by somebody who is either too stupid or too lazy (or has even worse personality flaws) to have the common courtesy to at least make an attempt to meet us at least half way.
The "one sentence per line" rule is the simplest and most obviously easy rule to fulfil the demands of -- and you are having problems with even something as simple as that?
As I have stated before, the main problem with your pages is your continued refusal to use links. Links are the whole point of this site. --prime mover (talk) 01:39, 3 July 2019 (EDT)
A decent sample size of the pages Prime.mover has been working on most recently will likely be representative of house style. These could be parsed to find the probability mass function of the words per line count. And then graded and less arbitrary warnings could be given. --Ascii 17:43, 2 July 2019 (EDT)
Thank you for your thoughtful response. Even just an arbitrary rule like 100 characters per line, that gets automatically checked, would be helpful.--Tkojar (talk) 18:44, 2 July 2019 (EDT)
This is not going to happen, for the simple reason that there can be no hard and fast rule about the number of characters in a line. Can't you just please learn how to use this site? --prime mover (talk) 01:13, 3 July 2019 (EDT)

## Updating png files does not work

I imported a new version of File:SimpleGraph.png but the old one is still being shown everywhere. I have tried purge in every place I can find it, but it is still showing the old version. When I try to re-import the new version, it tells me "

• A file with this name exists already, please check File:SimpleGraph.png if you are not sure if you want to change it.
• The upload is an exact duplicate of the current version of File:SimpleGraph.png.
• This file is a duplicate of the following file:

... but the pictures it shows me of File:SimpleGraph.png look exactly the same as the old one.

This is what it is supposed to look like:

and this is the old version which I tried to replace:

Is there a caching problem or something?

Many thanks if it can be fixed. --prime mover (talk) 06:08, 16 July 2019 (EDT)

Yeah there seems to be some sort of caching issue. We use several layers of caching not sure exactly which one was the issue. Let me know if it happens again. --Joe (talk) 09:46, 16 July 2019 (EDT)
It seems to be consistent. That is, it happens every time. --prime mover (talk) 10:24, 16 July 2019 (EDT)

## Direct Image Mappings and Inverse Image Mappings

I have gone some way down the route of tidying up the confusion that was Definition:Mapping Induced on Powerset, taking on board the various suggestions.

a) The terminology Definition:Direct Image Mapping and Definition:Inverse Image Mapping replace "induced mapping" throughout except in "also known as" sections. There may still be the need to amend names of results accordingly, but I think I may have caught them all.

b) Some words of explanation have been added pointing out the conceptual link between Definition:Image of Subset under Mapping (and the parallel concepts for Relation and Preimage) and Definition:Direct Image Mapping of Mapping (and likewise similar parallel concepts), calling attention to the fact that the one is an element of the other.

c) General tidying up and reorganising the various Also see sections.

There may be further room for improvement. Comments welcomed. --prime mover (talk) 08:32, 11 August 2019 (EDT)

## "Left" and "Right" -- page search puzzle

I created a new disambiguation page "Definition:Left" by entering "Left" in the Search panel and collating all the answers in the Definition namespace. As can be seen, nice big page.

But when I entered "Right" in the same search panel, it returned nothing. Nada, zilch, kabutnik ...

Whyyyy? --prime mover (talk) 16:36, 23 September 2019 (EDT)

## Mediawiki.js

I understand that I have been denied access to editing Mediawiki.js, so as to disallow me from adding more custom commands.

What are the channels for adding further custom shortcuts, or has a decision been made to prevent any further such additions? I know there's a limit to how many are practicable before the response starts to seriously deteriorate, and I know I've been adding quite a lot recently, but would it be possible to open a dialog on this?

Cheers, --prime mover (talk) 18:09, 1 October 2019 (EDT)

I'm not following. What page can't you edit? --Joe (talk) 11:42, 2 October 2019 (EDT)
Sorry, MathJax.js, not Mediawiki du-uh ...
MediaWiki:MathJax.js
Looks like I can't edit it either, I'm guessing there was some issue with the latest MediaWiki upgrade. I'll try to take a look and fix it later. --Joe (talk) 11:52, 2 October 2019 (EDT)
Should be working now, looks like there was a new group created specifically for these types of pages. --Joe (talk) 15:26, 2 October 2019 (EDT)
All good. Cheers. --prime mover (talk) 01:06, 3 October 2019 (EDT)

## latex playing up a bit

The latex on some pages, for instance this one, isn't rendering correctly.

Looks like this to me. Using the latest version of Chrome. Caliburn (talk) 19:51, 27 October 2019 (EDT)

Can't see it myself. Could be you've got some settings that are iffy, but I wouldn't know where to start. Problems I've had in the past are because of an inrelated 3rd party software package which subvert the default css settings. Tried doing an "inspect element" exercise? (I presume you've tried the obvious like flushing your cache.) Maybe you have a later Chrome than me, and once my machine gets itself together to adopt the latest one it will show the same problem you've got. --prime mover (talk) 02:19, 28 October 2019 (EDT)

## New direction

This site is obviously evolving in a completely different direction, so as from now I'm not going to bother doing any more tidying or making even the vaguest attempt to keep some sort of consistency between pages, because obviously people don't want this, they just want randomness, mess and unreadable disorder.

Your site, you do what you like with it, I can't be bothered to clean up after you all any more. --prime mover (talk) 17:05, 13 December 2019 (EST)

Certainly being the only moderator on the web site is an enormous and daunting task. And I fully understand a 'no more' response. The web site in my opinion has benefited from moderation and needs to continue to be moderated. It won't self organise. Nothing will turn contributors away faster than a lack of moderation.
An alternative response would be to look at how the moderation might be distributed. How could others be involved in the moderation? What does it take to be a moderator? How can the moderation be distributed?
Another response might be to look at how people contribute to the web site. Does it need to be officially recognised that contributors are not equal? While there is some recognition of this, maybe it needs to be more nuanced with more layers than currently exist, if that is possible. Should there more constraints on new contributors? How would contributors establish credentials? --Leigh.Samphier (talk) 01:45, 14 December 2019 (EST)
Some contributors pick up the general style and philosophy practically straight away, which suggests that, in general, the work needed to provide the overall look-and-feel is eminently learnable. Others just don't. And there was me thinking that mathematicians are by-and-large intelligent beings who have the mental wherewithal to learn how to do stuff. I'm obviously wrong. --prime mover (talk) 03:20, 14 December 2019 (EST)
To be involved in moderation you do not need any special rights. You can simply edit any page that clearly needs that. This is just a question of priorities, meaning that you have to allocate time to even attempt to fix anything. Only very special actions require additional rights. The problem may arise when one has to clean after some else's work. This can be problematic when the maths involved is foreign. But everything is up to you since there are no real penalties for not doing that. Maybe what we need is a campaign, e.g. "Nothing To Do November", when everyone is encouraged to prioritize that section over making new pages. --Julius (talk) 07:29, 14 December 2019 (EST)
Perhaps you write it neatly and correctly in the first place. --prime mover (talk) 17:21, 14 December 2019 (EST)
I am not sure if I am one of the users who have sparked your ire. If I am, then I apologize. I am pretty new around there and it takes me a while to get used to the house rules.I believe there are a handful of people who are experienced users of ProofWiki. So, maybe you should put some trust into those people if you think your workload is too much. Furthermore, I think that we should do something to promote this site further to attract more people. Then, they will come to the site, get experience and then they become reliable moderators and everything will go by itself after that point. In the meantime, I will try to get better and better with the content. It seems that being too keen to contribute is not the best idea. --AlienSnow (talk) 13:13, 17 December 2019 (EST)
There have been contributors in the past who seem to have scorned house style rules, on the grounds that their own style is better. Such contributors have caused a lot of work which has been onerous to accomplish. Don't worry about it, you're not too bad. --prime mover (talk) 14:53, 17 December 2019 (EST)
I'm trying to follow the house style rules - where I don't it's by accident/incompetence rather than by design. I'm generally good at editing Wiki pages, but writing $\LaTeX$ is new to me, so it's been a bit of a struggle at times to get it to co-operate, especially the map command and its eagerness to remove leading spaces - I wanted 2xy cos, which is what you get without using map, and it insisted on 2xycos so I had to encourage it with a ~! Whilst I find my feet I'm planning to only fix/tweak existing content and add anything that might be needed to support that fix, as I did with Factors of Sum of Two Even Powers which then needed Factorisation of z^n+a. I'll probably somewhat randomly skip around the various To Do pages - I suspect my next target will be Integer whose Digits when Grouped in 3s add to 999 is Divisible by 999 as that's a specific case of grouping n digits at a time to check divisibility by 999...99 (n digits), so you might see a growth in the various Divisibility test pages as a side-effect. --John Coupe (talk) 19:52, 28 December 2019 (EST)
Put \, before the map command is what I do. --prime mover (talk) 03:25, 29 December 2019 (EST)

## Ads Content

I was just surfing the site and I have just noticed that there are many ads that promote pseudo-scientific woo (Tarot card reading, Astrology stuff, etc.). I know that this site needs money in order to function, but I would advise to try to not promote such kind of ads because some external viewer might consider us some cranks or something similar and they might be discouraged from visiting the site. Also, if money is an issue, then maybe it is good to have a donation options where people who want the site to grow can donate some money for our cause.--AlienSnow (talk) 06:57, 23 December 2019 (EST)

Hadn't noticed, I'm afraid, I use adblocker.
Actually, tarot reading and astrology may be pseudo-scientific woo but it can be extremely profitable woo if you care to apply mathematics to it.
But I get your drift, and maybe something can be done to address this. I can't do anything about it myself, as I'm not at the sharp end of this (I think that would be Joe). --prime mover (talk) 11:04, 23 December 2019 (EST)
I've raised the issue with him, and en passant also inquired about possibilities for donation. — Lord_Farin (talk) 12:56, 23 December 2019 (EST)
Sorry I didn't respond earlier, I was offline for the Christmas holidays. With respect to running ads, we've tried donation based model for many years and it didn't come close to covering any of our costs. As for the specific ad content, it's presumably targeted. Not sure that anyone would judge the quality of this site based on their targeted ads (disclaimer: Not an ad expert)? Nevertheless, I'll look into limiting the ad categories. --Joe (talk) 10:32, 30 December 2019 (EST)

## Axiomatic Set Theory: a systematic approach

Having recently cracked open 2010: Raymond M. Smullyan and Melvin Fitting: Set Theory and the Continuum Problem (revised ed.), and really started to study it, I feel prepared to make a systematic approach to the subject of class theory, which up till now I have shied away from and plugged my ears and hoped it will go away.

Please bear in mind that a lot of the structure of the existing Category:Axioms is in the process of refinement, and so while the builders are in, the scaffolding may get in the way and I may tread mud onto the carpet.

Apologies to anyone who has been put off by my negativity on the subject in the past -- but I'm holed up in a hotel half way across the world with few books for company, and I have to do something. --prime mover (talk) 21:18, 17 January 2020 (EST)