## Have we ever lost any mathematics?

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The history of mathematics over the last 200 years has many occasions when the fundamental assumptions of an area have been shown to be flawed, or even wrong. Yet I cannot think of any examples where, as the result the mathematics itself had to be thrown out. Old results might need a new assumption or two. Certainly the rewritten assumptions often allow wonderful new results, but have we actually lost anything?

Note I would like to rule out the case where an area has been rendered unimportant by the development of different techniques. In that case the results still hold, but are no longer as interesting.

I wrote up a longer version of this question with a look at a little of the history: http://maxwelldemon.com/2012/05/09/have-we-ever-lost-mathematics/

Edit in response to comments

My thinking was about results that have been undermined from below. @J.J Green's example in the comments of Italian algebraic geometry seems like the best example I have seen. The trisection and individually wrong results do not seem to grow into areas, but certainly I would find interesting any example where a flawed result had built a small industry before it was found to be wrong. I am fascinated by mathematics that has been overlooked and rediscovered (ancient and modern) but that is perhaps a different question.

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If we had truly lost it, can you expect us to know enough about it to tell you? Gerhard "Still Looking For A Proof" Paseman, 2012.05.09 – Gerhard Paseman May 9 2012 at 22:03

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I had some mathematics in my pocket the other day, but I seemed to have lost it. Perhaps it is just buried in the mess of my desk... – Asaf Karagila May 9 2012 at 22:34

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Didn't something along these lines happen to Italian algebraic geometry in the 1930s? see en.wikipedia.org/wiki/… for example – J.J. Green May 9 2012 at 23:13

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This sounds like a different phenomenon from the one that you are refering to (is it?), but Indian Mathematics, Chinese Mathematics, Babylonian Mathematics, etc. were effectively "lost" (at least in large part), and have only recently been partially "rediscovered" as "archeology". More recently, 19th century invariant theory. It wasn't that they were false; it was that numerical methods became less valuable for these problems, because general methods were discovered, or else the calculations didn't draw enough attention because of lack of practical applications. – Daniel Moskovich May 10 2012 at 0:06

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According to cecm.sfu.ca/organics/covering/html/node4.html, "We have reached the point of decay in some areas. Richard Askey has observed that Gregory Chudnovsky knows things about hypergeometric functions that no one has understood since Riemann and that, with Chudnovsky's eventual passing, no one is likely to understand again." I've wondered what this refers to, but I've never asked Askey whether this quote is accurate or what he meant. – Henry Cohn May 10 2012 at 4:25
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## 9 Answers

There are "Lectures on Lost Mathematics" by B. Grünbaum. They were given at the University of Washington in 1975. The notes are available here

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Not to forget the book "A la recherche de la topologie perdue" edited by Guillot and Marin. – anonymous May 10 2012 at 6:27
@anonymous: why do you mention that book? Is it about lost math? – HJ May 13 2012 at 7:29

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Given that the title translates roughly as "Remembering Lost Topology," I'd assume so. – Daniel McLaury May 14 2012 at 7:19

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I was once told of a paper in homological algebra where a new class of functors was introduced, generalizing Ext and Tor. For some years they were studied, and various properties were proved. Finally someone managed to give a complete description of the entire class. It consisted of two elements, Ext and Tor. (Sorry, I don't have more details.)

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This is interesting, anyone have more details? – Edmund Harriss May 10 2012 at 9:44

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This reminds me of a colloquium talk I heard at Harvard some 40 years ago, in which a famous speaker generalized some results of Bott to an abstract setting. At the end, Bott, who was sitting in front, asked the speaker if he knew any examples of his theoretical objects other than, as I recall, sections of vector bundles over (possibly compact?) manifolds. The answer was "No, I don't." – roy smith May 10 2012 at 16:04

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Edmund, this may be related to your question. mathoverflow.net/questions/93716/… – roy smith May 10 2012 at 16:14
I heard the same story about a PhD thesis, where someone in the audience announced during the defense that the class of objects having the amazing properties described by the student was actually empty. I assume all such stories are apocryphal. – JeffE May 13 2012 at 8:47

I feel the answer is obviously "yes", and indeed that much of 19th century mathematics was lost, in a serious sense, for much of the 20th century. I was struck recently by discovering that Henry Fox Talbot, the photographic pioneer, had written on what is clearly the area around Abel's theorem for curves, and that probably it is a long time since anyone reconstructed what he was doing. Also that George Boole's main work, as far as his contemporaries were concerned, dropped out of sight within a couple of decades.

The fact is that mathematics now is (a) axiomatic and (b) dominated by a canon. I'm reminded of Bertrand Russell's nightmare - where, a century after his death, the last copy of the Russell-Whitehead Principia Mathematica is in danger of being thrown out by an ignorant librarian. It actually isn't obvious that even such a pioneering work makes it into the mathematical logic "canon" around later developments. (I hear protests!) Maybe it is worth pointing out Hilbert's interest in Anschauliche Geometrie, in other words non-axiomatic, intuitive geometry. And the canon should be "porous", as has been argued by some of the Moscow school. It seems quite an illuminating take on mathematics as a living tradition that simple accretion of "known results" is misleading.

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I always understood Russell's nightmare as reflecting insecurity in the lasting importance of his work, rather than the intelligence of its judges. – Pablo Zadunaisky Dec 16 at 22:34

Hilbert's $16^{\rm th}$ problem.

In 1923 Dulac "proved" that every polynomial vector field in the plane has finitely many cycles [D]. In 1955-57 Petrovskii and Landis "gave" bounds for the number of such cycles depending only on the degree of the polynomial [PL1], [PL2].

Coming from Hilbert, and being so central to Dynamical Systems developments, this work certainly "built a small industry". However, Novikov and Ilyashenko disproved [PL1] in the 60's, and later, in 1982, Ilyashenko found a serious gap in [D]. Thus, after 60 years the stat-of-the-art in that area was back almost to zero (except of course, people now had new tools and conjectures, and a better understanding of the problem!).

See Centennial History of Hilbert's 16th Problem (citations above are from there) which gives an excellent overview of the problem, its history, and what is currently known. In particular, the diagram in page 303 summarizes very well the ups and downs described above, and is a good candidate for a great mathematical figure.

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Grothendieck burned some of his works. I would probably think what he thought of is lost!

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I think it's clear from the body of the question that OP is asking about mathematics that was first accepted and then shown to be wrong, so this is not the kind of thing OP is asking for. – Gerry Myerson May 13 2012 at 5:40
Good point! Grothendieck's math almost always seem to be universally pursued though!! – unknown (google) May 13 2012 at 8:04

I don't know if this is an example of what you're asking. In mathematical logic, the Hilbert Program of the 1920's intended to come up with a finitary consistency proof and a decision procedure for analysis and set theory. Many luminaries including Hilbert himself, Bernays, Ackermann, von Neumann, etc. gathered in Göttingen for this purpose. Ackermann in 1925 published a consistency proof for analysis (that turned out to be incorrect) and many other promising results emerged. Then in 1931, Gödel's incompleteness theorem shut the whole thing down. Some valid theorems came out of it, but the program as a whole had to be (in some interpretations) completely abandoned.

http://en.wikipedia.org/wiki/Hilbert_program

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This is a great example, but it shows more that mathematics itself is not lost. In fact this, as part of the quest for the foundations is perhaps the canonical example. Doubt was cast on the foundations of the whole subject. Yet we only lost research directions rather than worlds of results. – Edmund Harriss May 12 2012 at 22:47

A exposition along this vein about Arabic mathematics.

http://www-history.mcs.st-andrews.ac.uk/HistTopics/Arabic_mathematics.html

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Volume II of Frege's Grundgesetze der Arithmetik (Basic Laws of Arithmetic) had already been sent to the press when Bertrand Russell informed him that what we now call "Russell's paradox" could be derived from one of his basic laws. I do not know to what extent Frege's work was known and publicly accepted (volume I was published 10 years before volume II), but this seems a clear case where a major body of work was undermined "from below", to use the words of the OP.

Upon learning of Russell's observation, Frege quickly wrote up an appendix to volume II, where he writes, "Hardly anything more unfortunate can befall a scientific writer than to have one of the foundations of his edifice shaken after the work is finished. This was the position I was placed in by a letter of Mr. Bertrand Russell, just when the printing of this volume was nearing its completion." (This translation appears in the Wikipedia article.)

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I guess Conways "lost proofs" qualify:

http://www.aimsciences.org/journals/pdfsnews.jsp?paperID=2447&mode=full

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The link doesn't work for me. – JeffE May 13 2012 at 8:44
I think it's clear from the body of the question that OP is asking about mathematics that was first accepted and then shown to be wrong, so this is not the kind of thing OP is asking for.  – Gerry Myerson May 13 2012 at 11:59
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