# User:Michael Hardy

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## Contents

## Barnstars

The Barnstar of Diligence
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Your endless devotion to wikipedia is amazing. Keep it up! Memming (talk) 12:57, 2 April 2010 (UTC) |

The Minor Barnstar
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A Barnstar for minor edits, but not a minor Barnstar! Thank you for your tireless work: you wikify tons of articles, and explain wikipedia' standards to tons of users! gala.martin (what?) 00:20, 8 April 2006 (UTC) |

The Original Barnstar
This barnstar is given to recognize particularly fine contributions to Wikipedia, and to let you know that your hard work is seen and appreciated. evrik 23:15, 10 August 2006 (UTC) |

The E=MC² Barnstar
For making mathematical and statistical articles readable for the layperson. Specifically, I ran across Second-order logic on random article and was extremely impressed by your work. Keep it up! Teke 18:37, 25 August 2006 (UTC) |

Thank you! Michael Hardy 19:24, 25 August 2006 (UTC)

The Original Barnstar
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I award you this barnstar in recognition of your continued work on statistics articles. Just about every statistics article I look at has some important contributions by you. Keep up the good work! Zvika 08:13, 5 January 2007 (UTC) |

- Thank you. Michael Hardy 22:49, 5 January 2007 (UTC)

The Original Barnstar
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To Michael Hardy, on the occasion of Minneapolis, Minnesota reaching featured article. With thanks -Susanlesch 23:23, 28 June 2007 (UTC) |

- Thank you. Michael Hardy 06:08, 29 June 2007 (UTC)

The Original Barnstar
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To Michael Hardy, on the occasion of Laplace transform and many other mathematics articles in which he showed his skill and vast knowledge of HTML, TeX and Wiki details. I learned a lot from your edits. With thanks --Lantonov 06:19, 1 September 2007 (UTC) |

Thank you. Michael Hardy 18:06, 2 September 2007 (UTC)

## The climate has changed here

Is it just me, or does one no longer frequently encounter illiterate legalistically inclined Wikipedians who angrily order around anyone claiming professional expertise in the topic of articles that said illiterate legalistically inclined Wikipedians want to work on for no reason? I haven't seen much of that for the past year or so.

## Some normative comments on editing Wikipedia articles

### Style tip

- "In ABCology, an
**X**is a blah blah blah."

is superior to

- "
is a term used by ABCologists to describe a blah blah blah."**X**

Here's another example (fictitious---a composite of several actual instances).

### Keep links simple when possible

Writing [[hyphen]]ated, [[logic]]al, [[cat]]s, [[evolution]]ary, [[rabbi]]nical, [[Egypt]]ian, [[dogma]]tic, [[apocrypha]]l, [[fur trade]]r, [[antagonist]]ic, [[algebra]]ic, [[legend]]ary etc., makes the whole word, not just the part in the brackets, appear as a clickable link, which links to the article whose title is in the brackets. The more complicated form can be used for things like [[philosophy|philosophies]].

Also, one does not need underscores as in [[prime_number_theorem]] or [[prime_number_theorem|prime number theorem]].

### a technical problem with templates

### a useful TeXnicality

### NEVER NEVER NEVER use \mbox within Wikipedia

Wikipedia:Manual of Style (mathematics)/Why you should never use \mbox within Wikipedia

This was a temporary workaround when we didn't have better things available and produces inferior results in some cases. **Worse:** In standard TeX usage (as opposed to the way TeX is used in Wikipedia and similar web sites) \mbox has a completely different function, so its use within Wikipedia just misleads people about what it's for.

### useful links

- Wikipedia:Graphic Lab/Images to improve
- http://meta.wikimedia.org/wiki/Help:Displaying_a_formula
- Wikipedia:Categories, lists, and series boxes
- List of mathematics categories
- How many people are watching a page?
- Wikipedia:Donating_copyrighted_materials

#### Wikipedia Mathematics Project

- Wikipedia:WikiProject Mathematics • Talk
- Wikipedia:WikiProject Mathematics/Typography • talk
- Wikipedia:WikiProject Mathematics/Current activity
- Wikipedia:WikiProject Mathematics/Nav
- Wikipedia:Pages needing attention/Mathematics/Lists
- Wikipedia:WikiProject Mathematics/Graphics, Wikipedia:Requested pictures
- Wikipedia:WikiProject Mathematics/Article alerts
- Wikipedia:Reference desk/Mathematics
- User talk:Nageh/mathJax
- http://www.mediawiki.org/wiki/Requests_for_comment/Reduce_math_rendering_preferences

#### Statistics Project

#### Lists are better than categories

User:Michael Hardy/Lists are better than categories

## How many times was a particular Wikipedia article viewed in a particular month?

Find out from this site.

## Shortest path from one article to another

## Some Wikipedia articles I originated

### On topics not within my professional qualifications

John Gillespie Magee, Junior, self-evidence, tidal resonance, Woods Hole Oceanographic Institution, list of religious topics (Many others have contributed to that one.) Fellowship of Reason, list of optical topics, iridescence, sylvanshine, Foundation for the Advancement of Art, Elisha Otis, Roman Republic (19th century), effect of sun angle on climate, Marlon Knauer, Shyamala Rajender v. University of Minnesota, Karlis Kaufmanis

### On probability, statistics, probabilists, and statisticians

list of statistical topics, Gauss–Markov theorem, Completeness (statistics), Sufficiency (statistics), logit, Kolmogorov's zero-one law, martingale, margin of error, zeta distribution, Zipf's law, confidence interval, Bruno de Finetti, Maxwell's theorem, law of total probability, law of total expectation, law of total variance, Galton–Watson process, coherence (philosophical gambling strategy), cumulant, canonical correlation, Wishart distribution, Rao–Blackwell theorem, Student's t-distribution, Wiener process, errors and residuals in statistics, Seymour Geisser, prediction interval, rankit, continuity correction, Studentized residual, Studentized range, Cramér–Rao inequality

Francis Ysidro Edgeworth (a stub; if it's a long article when you read this, then someone else has contributed),

ancillary statistic, empirical Bayes method, Herbert Robbins, memorylessness, factorial moment, rule of succession, conditional independence, pairwise independence, prior probability distribution, infinite divisibility, a term used in physics, probability theory, and several other disciplines, Schrödinger method, Vandermonde's identity, an inequality on location and scale parameters, compound Poisson distribution,

In estimation of covariance matrices, I describe what seems to me to be a surprisingly subtle and elegant application of linear algebra. I have no idea who originated it; I seem to recall that it is in Morris Eaton's book on multivariate statistics, and I suppose it is in lots of others. In that argument you find out why it is sometimes better to view a scalar as the trace of a 1×1 matrix than as a mere scalar and then to apply certain matrix decompositions to it.

Lévy process, Wigner semicircle distribution, multinomial distribution, Ewens's sampling formula, imputation (statistics), law of total cumulance, copula (statistics) (incorporating some material from Sklar's theorem, which was created by User:Oo64eva and is now a redirect page), normally distributed and uncorrelated does not imply independent, list of stochastic processes topics, method of moments (statistics), method of moments (probability theory)

Eduard Helly, David Blackwell (both stub articles; if they're more than stubs when you see them, then more recent edits have been done)

le Cam's theorem, McCullagh's parametrization of the Cauchy distributions, Lilliefors test, empirical distribution function--still a stub article at this time, Poisson regression, Shapiro–Wilk test, location-scale family, Behrens–Fisher problem (now still a stub), Hausdorff moment problem, Hamburger moment problem, Stieltjes moment problem, Chinese restaurant process, indecomposable distribution, Wick product, Robbins lemma, Fisher's inequality, Chernoff's distribution (a stub, but it clearly gives the definition), Lack-of-fit sum of squares, Bhatia–Davis inequality, Samuelson's inequality, Popoviciu's inequality on variances, Raikov's theorem, An Essay towards solving a Problem in the Doctrine of Chances, Lester Dubins, Behrens–Fisher distribution, Minimum chi-square estimation, Poisson point process

### On other mathematical topics

inequality of arithmetic and geometric means, incidence algebra, Euler characteristic, stereographic projection, common logarithm, Dirichlet kernel,

exponential growth (a concept that "laymen" take to mean very fast growth, but which has a technical definition that need not imply great rapidity)

empty product This explains why, when you
multiply no numbers at all, you get 1, and why
0^{0} is *almost always* 1, and should
be taken to be 1 for the purposes of set theory,
combinatorics, probability, and power series.

binomial type, Sheffer sequence, umbral calculus, Bell numbers, Hermite polynomials, Chebyshev polynomials, Bernoulli polynomials, Gian-Carlo Rota

Archimedes Palimpsest This one mentions ancient history, mathematics, physics, engineering, an art museum, a federal lawsuit, and a very old hierarchical religious organization, in a very short space, without undue cramming;

How Archimedes used infinitesimals, Archimedean property, Eric Temple Bell, Arthur Cayley, Riemann–Stieltjes integral, bounded variation, Ferdinand von Lindemann, Charles Hermite,

orthogonal polynomials (Do **not** move that article
to "orthogonal polynomial" under a delusion that that would
conform to the convention of titling an article "dog" rather
than "dogs". That would be absurd. There is no such thing
as an orthogonal polynomial; there is such a thing as
orthogonal polynomials.),

pointwise convergence, Bernstein polynomial, George Boolos, Cantor's theorem, Löwenheim–Skolem theorem, second-order logic (much expanded by others since I started it)

Cantor's first uncountability proof. This proof shows that the set of all real numbers is uncountable, but this proof is **not** a diagonal argument! This article has since been sweepingly revised by user:RJGray, who added material on a dispute over whether the proof is constructive and material derived from letters between Cantor and colleagues.

inclusion-exclusion principle, linearly ordered group, Boolean prime ideal theorem, uniform norm, Galton–Watson process, coherence (philosophical gambling strategy), dominated convergence theorem, Robertson–Seymour theorem, double integral (not the same as an "iterated integral"; see the article), Fubini's theorem, mathematical logic, Girard Desargues, Desargues' theorem, parallelogram law, Hamel basis, König's theorem, Schur complement (that article needs more work), combinatorial species (I left this one a stubby article that was barely a definition and two or three more-or-less obvious examples; AlexG has since added an account of operations on combinatorial species and lots of essential facts), A simple proof that 22/7 exceeds pi, Putnam Competition, Stone's representation theorem for Boolean algebras, Separation of variables, moment (a disambiguation page), list of mathematical examples (still in its infancy) Möbius transform, cross-ratio, Morera's theorem, Mahler's theorem, Cauchy principal value, Pincherle derivative

Radius of convergence -- This article includes an example
of the fact that *complex* numbers are sometimes simpler
than real numbers; they allow us to quickly find the radius
of convergence of a power series in which the coefficients
are Bernoulli numbers. (As you see from the previous
sentence, I firmly believe in splitting infinitives on
occasion.) Faà di Bruno's formula,

I moved the anonymously written "absolutely continuous" page to absolute continuity and rewrote it from scratch, including both absolute continuity of real functions, and absolute continuity of measures and the Radon–Nykodym theorem.

An infinitely differentiable function that is not analytic -- Although this is merely the usual example, I explained (albeit tersely, so far) its relevance to Schwartz's theory of generalized functions: One can construct test functions (i.e., infinitely differentiable functions with bounded support) with prescribed behavior on an interval. The existence of such functions must be known before we can confidently say that Schwartz's whole theory is not vacuous.

Moreau's necklace-counting function, cyclotomic identity,
proof that holomorphic functions are analytic,
branch point, Bell polynomials, Pedoe's inequality,
Hadwiger's theorem
(a stub; if it's a long article when you read this, then
someone else has contributed), defect (geometry)
(a fairly terse article so far....), Dandelin spheres,
matrix exponential (others have added material to
that one), noncrossing partition,
uses of trigonometry, Bohr–Mollerup theorem,
characterization (mathematics),
list of Boolean algebra topics, germ (mathematics),
Lissajous curve -- someone has since edited that one
by adding illustrations, Cauchy product, Gibbs phenomenon
-- a number of people have worked on this one,
Schrödinger method, Vandermonde's identity,
list of Fourier analysis topics, Muirhead's inequality, Stanley's reciprocity theorem, exponential formula, method of distinguished element, Stirling transform, osculating circle, list of circle topics,
list of knot theory topics, Cantor's back-and-forth method, list of set theory topics, rencontres numbers, Bernstein's theorem, multiplicities of entries in Pascal's triangle, Dobinski's formula, Brahmagupta–Fibonacci identity (originally titled *Fibonacci's identity*; that is now a disambiguation page), alternating permutation, spread polynomials, Faulhaber's formula, Appell sequence, caloric polynomial, Johan Frederik Steffensen---stubby so far..., Lester's theorem, Monge's theorem, polar sine, Hermite–Hadamard inequality, Steiner inellipse, Marden's theorem, (Lommel–Weber function After I created this, it was found that three articles on this topic existed under different titles, which then got merged, so this page now redirects to another.),
Regiomontanus' angle maximization problem, Bloch's theorem (complex variables),
List of topics named after Bernhard Riemann, Cavalieri's principle, Napkin ring problem (on a startling result in elementary geometry; the natural way to prove this is by Cavalieri's principle, but some authors perversely persist in relying only on other methods), Lune of Hippocrates, Mollweide's formula, Bonse's inequality,
Landau's algorithm (a stub article that identifies the purpose and the creator of the algorithm but doesn't describe it; hopefully others, if not I, will expand it), List of topics named after Fibonacci, List of topics named after Augustin-Louis Cauchy, Harold Edwards (mathematician), *n*Lab, Erdős–Kac theorem, Triangular array (currently stubby, but with a fairly good list of examples), List of topics named after Karl Weierstrass, Weierstrass substitution, Gerald J. Toomer — I created this one in somewhat stubby form after I noticed that dozens of Wikipedia articles mention this person; before creating it I put links to it into dozens of articles,
Ptolemy's table of chords, Haynsworth inertia additivity formula, Patrick Billingsley, Integral of the secant function, Tikhonov's theorem (dynamical systems), Śleszyński–Pringsheim theorem, Tree of primitive Pythagorean triples, Hermite's cotangent identity, Kummer's theorem, Niven's theorem, Sendov's conjecture, List of things named after Charles Hermite, Loximuthal projection, Mean-periodic function, Tsit Yuen Lam (I translated the German article about him),
Grace–Walsh–Szegő theorem, Cohn-Vossen's inequality, Cyclic sieving (I created this in stubby form, and others expanded it far beyond that)

## Puzzle

See if you can spot the difference between this:

and this:

Without looking at the TeX code, and guess how and—perhaps more subtly—why the difference was achieved.

- That's subtle! Here is a cruder way of achieving the same effect:
- --RockMagnetist (talk) 04:53, 29 September 2010 (UTC)
- Actually this latter version by RockMagnetist is incorrect. The correct version, however, doesn't seem to work with our maths module, so I must show it in the commented spoiler below.

- Yea, I got the visual difference quickly but am uncertain what RockMagnetist is perceiving. I was going to put my observation up here and then realized when I saw the spoiler notes, that it would in fact be a spoiler. For those of us non-mathematicians, we certainly take some things for granted... Regards, Steve... Stevenmitchell (talk) 05:24, 8 March 2011 (UTC)

- – b_jonas 12:23, 7 December 2010 (UTC)

**My answer** to the question above is this: When "+" is a binary operator, there is a space on each side of it, thus: 3 + 5. But when it is a unary operator, there isn't, thus: +5. In TeX, when you write +5 at the beginning of a line, the software construes it as unary since nothing comes before it (on the same line). But if you want it to be read as binary, you write {} +5, and then there's something (albeit invisible) before it, so it gets rendered as + 5. Michael Hardy (talk) 19:49, 12 May 2012 (UTC)

http://www.mathpages.com

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Techblog

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Titchmarsh convolution theorem

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User:Michael Hardy/Everest (mathematical competition) (written primarily by User:Luka.W.B.)

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