# Which math paper maximizes the ratio (importance)/(length)?

My vote would be Milnor's 7-page paper "On manifolds homeomorphic to the 7-sphere", in Vol. 64 of Annals of Math. For those who have not read it, he explicitly constructs smooth 7-manifolds which are homeomorphic but not diffeomorphic to the standard 7-sphere.

What do you think?

Note: If you have a contribution, then (by definition) it will be a paper worth reading so please do give a journal reference or hyperlink!

Edit: To echo Richard's comment, the emphasis here is really on short papers. However I don't want to give an arbitrary numerical bound, so just use good judgement...

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You should probably bound the length, cuz otherwise you could just pick your favorite paper of Ratner, Grothendieck, Thurston, et cetera and the importance blows everything else away. – Richard Kent Dec 1 '09 at 1:41
Or Gromov, "from whose sentences people have written theses" (as I have seen someone write somewhere) – Mariano Suárez-Alvarez Dec 1 '09 at 2:31
The award for the corresponding question for paper titles would have to go to "H = W". Meyers and Serrin, Proc. Nat. Acad, Sci. USA 51 (1964), 1055-6. – John D. Cook Jan 6 '10 at 2:49
It also depends on what you define a "paper". A number of fundamental results have been announced, and their proof has been sketched, in the C.R. Acad. Sci. - and all of them are four pages long. – Delio Mugnolo Nov 9 '13 at 14:48

The little paper by John McKay on Graphs, singularities, and finite groups is a nice example.

Graphs, singularities, and finite groups. The Santa Cruz Conference on Finite Groups (Univ. California, Santa Cruz, Calif., 1979), pp. 183--186, Proc. Sympos. Pure Math., 37, Amer. Math. Soc., Providence, R.I., 1980.

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There are a very large number of very concise papers written in the USSR, back when it existed.

A good example would Beilinson's paper "Coherent sheaves on $\mathbb{P}^n$ and problems of linear algebra." It's probably not quite as earth-shaking as Milnor's paper, but it's also only slightly more than 1 page long.

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Well, omiting all details is not the same thing as being space-efficient! :P – Mariano Suárez-Alvarez Dec 1 '09 at 2:03
Can anyone sum up what Beilison's paper is about to me? Many thanks. – darij grinberg Jan 5 '10 at 23:36

Any of three papers dealing with primality and factoring that are between 7 and 13 pages:

First place: Rivest, R.; A. Shamir; L. Adleman (1978). "A Method for Obtaining Digital Signatures and Public-Key Cryptosystems". Communications of the ACM 21 (2): 120–126.

Runner-up: P. W. Shor, Algorithms for quantum computation: Discrete logarithms and factoring, Proc. 35nd Annual Symposium on Foundations of Computer Science (Shafi Goldwasser, ed.), IEEE Computer Society Press (1994), 124-134.

Honorable mention: Manindra Agrawal, Neeraj Kayal, Nitin Saxena, "PRIMES is in P", Annals of Mathematics 160 (2004), no. 2, pp. 781–793.

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Does it count if you publish in a conference proceedings with a 10-page limit (although I did buy an extra page). The full version, SIAM J. Computing 26: 1484-1509 (1997), was 26 pages. – Peter Shor Mar 19 '10 at 13:57
I'd say it counts and then some. I never saw a bunch of military types getting all excited and nervous about a paper on abelian categories or natural proofs and trying to understand the results. – Steve Huntsman Mar 19 '10 at 14:09

Beilinson and Bernstein's paper "Localisation de $\mathfrak g$-modules" is probably the most important in geometric representation theory, and is roughly 3 pages long.

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It's available on the internet in the sense that I can send you a scan. – Ben Webster May 4 '11 at 23:04
thanks! please send it then to %first name%.%second name%@gmail.com – Dima Sustretov May 4 '11 at 23:45

Kazhdan's paper "On the connection of the dual space of a group with the structure of its closed subgroups" introduced property (T) and proved many of its standard properties. And it's only 3 pages long (and it contains a surprisingly large number of details for such a short paper!)

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My favourite is the following tiny, self-contained article:

"Uniform equivalence between Banach Spaces" by Israel Aharoni & Joram Lindenstrauss, Bulletin of the American Mathematical Society, Volume 84, Number 2, March 1978, pp.281-283.

http://www.ams.org/bull/1978-84-02/S0002-9904-1978-14475-9/S0002-9904-1978-14475-9.pdf

(in which the authors prove that there exist two non-isomorphic Banach spaces that are Lipschitz homeomorphic.)

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I would recommend one very short "paper" by Grothendieck in some IHES publications has defined algebraic de Rham cohomology. (I don't think it maximizes the ratio in question, but it is an interesting one, anyway.)

BTW, it was actually part of a mail to Atiyah. It begins with 3 dots! (Maybe some private conversation was omitted). Of course, sometimes Grothendieck wrote long letters (e.g. his 700-page letter to Quillen "pursuing stacks" or his 50-page letter to Faltings on dessin d'enfant).

Also, I think Grothendieck had a (short?) paper with a striking title called "Hodge conjecture is false for trivial reason", in which he pointed out that the integral Hodge conj. is not true, one has to mod out by torsion, i.e. tensored with Q.

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"The general Hodge conjecture is false for trivial reasons." I'm nitpicking, but it's easily my favorite title of a math paper ever. – Harrison Brown Dec 1 '09 at 3:28
What, you don't like "Zaphod Beeblebrox's brain and the fifty-ninth row of Pascal's triangle"? – Qiaochu Yuan Dec 1 '09 at 19:57
Funny as that is, it doesn't have the same oomph to it as "X is false for trivial reasons." While we're on the subject of funny titles, though, I like "Mick gets some (the odds are on his side)", which makes no sense whatsoever as a paper title until you realize what the paper's about! – Harrison Brown Dec 2 '09 at 2:01
Correcting the title is not just nitpicking. The paper is about a generalisation of the Hodge conjecture concerning a characterisation of the filtration on rational cohomology induced by the Hodge filtration. It deals with rational cohomology and so is not concerned with the failure of the (non-generalised) Hodge conjecture for integral cohomology. The latter result is due to Atiyah-Bott. – Torsten Ekedahl Mar 19 '10 at 5:24
My favorite title is P. Cartier, Comment l'hypothese de Riemann ne fut pas prouvee [How the Riemann hypothesis was not proved], Seminar on Number Theory, Paris 1980-81 (Paris, 1980/1981), pp. 35-48, Progr Math 22, Birkhauser, Boston, 1982, MR 85f:11035. – Gerry Myerson Sep 23 '10 at 6:42

Depending on how strict you are, this might not qualify as a paper. Hilbert's 1900 ICM talk in which he posed his 23 problems.

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Serre's GAGA isn't as short as some of the others, but it's still just over 40 pages (which is quite short by the standards of Serre/Grothendieck-style algebraic geometry at the time -- e.g. FAC is about 80 pages, and of course there are things like EGA...), and it's still GAGA.

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A natural choice is Riemann's "On the Number of Primes Less Than a Given Magnitude" at only 8 pages long...

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In theoretical CS, there's the Razborov-Rudich "natural proofs" paper, which weighs in at 9 pages. After introducing and defining the terminology, and proving a couple of simple lemmas, the proof of the main theorem takes only a couple of paragraphs, less than half a page if I recall correctly.

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Noam Elkies, The existence of infinitely many supersingular primes for every elliptic curve over Q, Invent. Math. 89 (1987), 561-568.

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Because its length (and simplicity), this was the first paper I ever completely read! – David Zureick-Brown Dec 1 '09 at 4:49

Riemann's Habilitationsschrift, On the hypotheses which lie at the foundation of geometry, was the start of Riemannian Geometry. An English translation took up 6 pages in Nature.

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That is not a paper: it's the Habilitation $\textit{lecture}$ Riemann gave, which was only published posthumously. – Victor Protsak May 21 '10 at 2:19

Mordell, L.J., On the rational solutions of the indeterminate equations of third and fourth degrees, Proc. Camb. Philos. Soc. 21 (1922), 179–192.

In this paper he proved the Mordell-Weil theorem for elliptic curves over $\mathbb{Q}$ (the group of rational points is finitely generated), and he stated the Mordell conjecture (curves of genus >1 over $\mathbb{Q}$ have only finitely many points), which was one of the most important open problems in mathematics until Faltings proved it in 1983.

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H. Lebesgue, Sur une généralisation de l’intégrale déﬁnie, Ac. Sci. C.R. 132 (1901), 1025– 1028.

The beginning of measure theory as we know it, and a very short paper.

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– bezirsk Jun 26 '13 at 11:27
I was going to link to this paper. It's one of the most beautiful papers in signal to noise ratio sense. – Guido Jorg Sep 29 '14 at 13:22

My mention goes to V. I Lomonosov's "Invariant subspaces for the family of operators which commute with a completely continuous operator", Funct. Anal. Appl. 7 (1973) 213-214, which in less than two pages demolished numerous previous results in invariant subspace theory, many of which previously took dozens of pages to prove. It also kick-started the theory of subspaces simultaneously invariant under several operators, where it continues to be useful today. It's highly self-contained, using only the Schauder-Tychonoff theorem, if I remember correctly.

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I also like Lomonosov and Rosenthal's "The simplest proof of Burnside's theorem on matrix algebras" that proves that a proper subalgebra of a matrix algebra over an algebraically closed field must have a non-trivial invariant subspace. 3 pages. – Dima Sustretov May 4 '11 at 23:40

The so called "Weil conjectures" are in the last pages of André Weil's short paper in 1949, "Numbers of solutions of equations in finite fields", Bulletin of the American Mathematical Society 55: 497–508. They probably were around before though.

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I get this nominee from Halmos...

E. Nelson, "A Proof of Liouville's Theorem", Proc. Amer. Math. Soc. 12 (1961) 995

9 lines long. Not the shortest paper ever, but maximizes importance/length ...

http://www.jstor.org/stable/2034412

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William C. Waterhouse, An Empty Inverse Limit, Proceedings of the American Mathematical Society, Vol. 36, No. 2 (Dec., 1972), p. 618. The body of the paper is only 6 lines. – Richard Kent Dec 1 '09 at 17:29
Other shorties... from sci.math in 1994. P.H. Doyle: Plane Separation, Proc. Camb. Phil. Soc. 64 (1968) 291; MR 36#7115. H. Furstenberg: On the Infinitude of Primes, Amer. Math. Monthly 62 (1955) 353; MR 16-904. D. Lubell: A Short Proof of Sperner's Lemma, J. Comb. Theory, Ser. A, vol.1 no. 2 (1966) 299; MR 33#2558. – Gerald Edgar Dec 2 '09 at 0:21

Jürgen Moser (1965), On the Volume Elements on a Manifold , Transactions of the American Mathematical Society, Vol. 120, No. 2 (Nov., 1965), pp. 286-294

http://www.jstor.org/stable/1994022

Besides the many powerful applications of the famous "Moser argument" (or "Moser trick"), the local version gives a very nice and elegant proof of the classical Darboux Theorem.

(For a nice summary of this and other papers by Jürgen Moser, I would recommend http://www.math.psu.edu/katok_a/pub/Moserhistory.pdf (a short discussion of the paper mentioned above can be found at p.17-18))

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One of the shortest papers ever published is probably John Milnor's Eigenvalues of the Laplace Operator on Certain Manifolds, Proceedings of the National Academy of Sciences of USA, 1964, p. 542

He shows that a compact Riemannian manifold is not characterized by the eigenvalues of its Laplacian. It takes him little more than half of a page.

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Also on the same topic: Also Kac's Can one hear the shape of a drum? is pretty short. – Delio Mugnolo Nov 9 '13 at 14:53

Drinfeld and Simpson's B-Structures on G-Bundles and Local Triviality, Mathematical Research Letters 2, 823-829 (1995) comes in at under seven pages and has been quite important in all the work done on principal G-bundles (such as the geometric Langlands' program).

In particular, it proved the double quotient description of G-bundles on curves (for reductive G) which had previously only been proved for $G = SL_n$ by Beauville and Laszlo.

The paper can be found here.

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Endre Szemeredi's paper on the Regularity Lemma is just 3 pages long. I think that is a good candidate as well.

Szemerédi, Endre (1978), "Regular partitions of graphs", Problèmes combinatoires et théorie des graphes (Colloq. Internat. CNRS, Univ. Orsay, Orsay, 1976), Colloq. Internat. CNRS, 260, Paris: CNRS, pp. 399–401,

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Although didn't it appear beforehand in the monstrously complicated proof of Szemeredi's theorem? – Harrison Brown Dec 2 '09 at 1:36

How about Leonid Levin (1986), Average-Case Complete Problems, SIAM Journal of Computing 15: 285-286? Quite important in complexity theory, and only two pages long, although very, very dense.

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John Nash's "Equilibrium Points in n-Person Games" is only about a page and is one of the most important papers in game theory.

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Nowadays this sort of paper would not get published at all, and would likely appear just as an answer on MathOverflow. – Andrej Bauer Nov 7 '11 at 14:26
A stable link is: web.mit.edu/linguistics/events/iap07/Nash-Eqm.pdf – Todd Trimble Dec 14 '13 at 0:21

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Robert Aumann's "Agreeing to Disagree" paper, at 3 pages of length, is one of the most important papers in its field.

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-- -- I disagree. -- – Włodzimierz Holsztyński Sep 28 '14 at 18:36

Jannsen, Uwe (1992), "Motives, numerical equivalence and semi-simplicity", Inventions math. 107: 447–452.

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It's not a paper, and it's not groundbreaking, but it's short!

A One-Sentence Proof That Every Prime $p\equiv 1\pmod 4$ Is a Sum of Two Squares D. Zagier The American Mathematical Monthly, Vol. 97, No. 2 (Feb., 1990), p. 144 http://www.jstor.org/pss/2323918

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That's a beautiful one indeed. And it also has lot of potential for the (obscurity of the idea)/(line count) competition :P – Mariano Suárez-Alvarez Jan 6 '10 at 3:39
And you can see that sentence for only $12 at JSTOR! – I. J. Kennedy May 17 '10 at 0:37 Save 12 bucks: The involution on a finite set$S = \{(x,y,z) \in \mathbb{N}^3 : x^2 +4yz = p \} $defined by: $(x,y,z) \mapsto \left\{ \begin{array}{cc} (x+2z,z,y-x-z) & \text{if } x < y-z \\ ( 2y-x, y, y-x+z ) & \text{if } y-z < x <2y \\ ( x-2y, x-y+z, y ) & \text{if } x > 2y \end{array} \right.$ has exactly one fixed point, so$|S|$is odd and the involution defined by$(x,y,z) \mapsto (x,z,y)\$ also has a fixed point. – Zavosh May 21 '10 at 11:46
One thing I've always wondered - is there any intuition behind the involution? – dvitek Sep 30 '10 at 4:16
+1 to Mariano and drvitek. It is hardly a memorable proof. That is, unless you have some special insight or photographic memory, you're not going to remember how that involution goes. I once wrote a crabby blog post about this proof, here: topologicalmusings.wordpress.com/2008/05/04/… – Todd Trimble Nov 7 '11 at 22:09

Barry Mazur "On Embeddings of Spheres", Bull. AMS v 65 (1959) only 5 1/2 pages. It introduced the method of infinite repetition in topology and allowed the proof the generalized Schoenflies conjecture.

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The one-page paper

Golay, Marcel J. E.: "Notes on Digital Coding", Proc. IRE 37, p. 657, 1949,

which introduces the Golay code.

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It's not even a whole page! – Robin Chapman Nov 2 '10 at 7:41
I first came across Golay codes when studying electrical engineering - I recal looking up this paper, thinking I understood it but I still had to experiment with examples for several days to really believe that such a simple thing could be such a powerful error correcting code. – WetSavannaAnimal aka Rod Vance May 20 '11 at 13:01