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Gödel's Theorem in 15 Minutes (English, Latvian, Russian)

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Diploma

What is Mathematics:
Gödel's Theorem and Around

Hyper-textbook for students
by Karlis Podnieks, Professor
University of Latvia
Institute of Mathematics and Computer Science

An extended translation of the 2nd edition of my book " Around Goedel's theorem" published in 1992 in Russian (online copy).

Table of contents


Diploma
Creative Commons License This work is licensed under a Creative Commons License and is copyrighted © 1997-2008 by  me, Karlis Podnieks.

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Horizons of Truth:
Gödel Centenary 2006

Wolfgang Haken and Kenneth Appel:
see pictures in
European Mathematical Society, Newsletter No. 46, December 2002, pp. 15-19.
Except the above ones, how many pictures of Haken and Appel can be found on the web?
Another one:
http://unhmagazine.unh.edu/sp02/mathpioneers.html
Another one:
http://www.ehu.es/~mtwmastm/PresentacionSCTM06.pdf
And that's all?
October 8, 2007: Kenneth Appel - 75!
June 21, 2008: Wolfgang Haken - 80!

My Hall of Fame

Plato    I. Kant   G. Cantor   H. Poincaré   D. Hilbert   E. Zermelo   K. Gödel   P. Cohen

See portraits of these brilliant people in the MacTutor History of Mathematics archive
at the University of St Andrews. And in Wikipedia.

What is Mathematics? (My Main Theses)

I define mathematical theories as stable self-contained (autonomous?) systems of reasoning, and formal theories - as mathematical models of such systems. Working with stable self-contained models mathematicians have developed their ability to draw a maximum of conclusions from a minimum of premises. This is why mathematical modeling is so efficient (my solution to the problem of "The Incomprehensible Effectiveness of Mathematics in the Natural Sciences" - as put by Eugene Wigner).

For me, Goedel's results are the crucial evidence that stable self-contained systems of reasoning cannot be perfect (just because they are stable and self-contained). Such systems are either non-universal (i.e. they cannot express the notion of natural numbers: 0, 1, 2, 3, 4, ...), or they are universal, yet then they run inevitably either into contradictions, or into unsolvable problems.

For humans, Platonist thinking is the best way of working with stable self-contained systems. Thus, a correct philosophical position of a mathematician should be: a) Platonism - on working days - when I'm doing mathematics (otherwise, my "doing" will be inefficient), b) Advanced Formalism - on weekends - when I'm thinking "about" mathematics (otherwise, I will end up in mysticism). (The initial version of this aphorism is due to Reuben Hersh / picture).

Next step

The idea that stable self-contained system of basic principles is the distinctive feature of mathematical theories, can be regarded only as the first step in discovering the nature of mathematics. Without the next step, we would end up by representing mathematics as an unordered heap of mathematical theories!

In fact, mathematics is a complicated system of interrelated theories each representing some significant mathematical structure (natural numbers, real numbers, sets, groups, fields, algebras, all kinds of spaces, graphs, categories, computability, all kinds of logic, etc.).

Thus, we should think of mathematics as a "two-dimensional" activity. Sergei Yu. Maslov could have put it as follows: most of a mathematician's working time is spent along the first dimension (working in a fixed mathematical theory, on a fixed mathematical structure), but, sometimes, he/she needs also moving along the second dimension (changing his/her theories/structures or, inventing new ones).

Do we need more than this, to understand the nature of mathematics?

What is Mathematics?

Four definitions of mathematics provably equivalent to the above one (see Section 1.2):

Mathematics is the part of science you could continue to do if you woke up tomorrow and discovered the universe was gone.
I do not know the author of this elegant definition put on the web by Dave Rusin.

... the human mind has first to construct forms independently, before we can find them in things. ... knowledge cannot spring from experience alone, but only from the comparison of the inventions of the intellect with observed fact.
Albert Einstein, see The Schiller Institute

In mathematics you don't understand things. You just get used to them.
John von Neumann, see Quotations by John von Neumann).

Mathematicians are mad tailors: they are making "all the possible clothes" hoping to make also something suitable for dressing...
Stanislaw Lem, "Summa Technologiae" (sorry - my own English translation, the initial version of this aphorism may be due to David van Dantzig, see Quotations by David van Dantzig)

Gödel and Einstein, by Torkel Franzén

Why is Einstein much more popular than Gödel?
Kurt Godel in Blue Hill, by Peter Suber

Wir muessen wissen -- wir werden wissen!
David Hilbert's Radio Broadcast, Koenigsberg, 8 September 1930
(audio record published by James T.Smith, and translations in 7 languages published by Laurent Siebenmann).

"Hilbert and Goedel never discussed it, they never spoke to each other. ... They were both at a meeting in Koenigsberg in September 1930. On September 7th Goedel off-handedly announced his epic results during a round-table discussion. Only von Neumann immediately grasped their significance..." (G.J.Chaitin' s lecture, 1998, Buenos Aires)

Table of contents

1. Platonism, intuition and the nature of mathematics

  • 1.1. Platonism - the philosophy of working mathematicians
  • 1.2. Investigation of stable models - the true nature of the mathematical method
  • 1.3. Intuition and axioms
  • 1.4. Formal theories
  • 1.5. Hilbert's program
  • 2. Axiomatic set theory

  • 2.1. The origin of Cantor's set theory
  • 2.2. Formalization of Cantor's inconsistent set theory
  • 2.3. Zermelo-Fraenkel axioms
  • 2.4. Around the continuum problem
  • 2.4.1. Counting infinite sets
  • 2.4.2. Axiom of constructibility
  • 2.4.3. Axiom of determinacy
  • 2.4.4. Ackermann's set theory (Church thesis for set theory?)
  • 3. First order arithmetic

  • 3.1. From Peano axioms to first order axioms
  • 3.2. How to find arithmetic in other formal theories
  • 3.3. Representation theorem
  • 4. Hilbert's Tenth problem

  • 4.1. History of the problem. Story of the solution
  • 4.2. Plan of the proof
  • 4.3. Investigation of Fermat's equation
  • 4.4. Diophantine representation of solutions of Fermat's equation
  • 4.5. Diophantine representation of the exponential function
  • 4.6. Diophantine representation of binomial coefficients and factorial function
  • 4.7. Elimination of restricted universal quantifiers
  • 4.8. 30 ans apres
  • 5. Incompleteness theorems

  • 5.1. Liar's paradox
  • 5.2. Self-reference lemma
  • 5.3. Goedel's incompleteness theorem
  • 5.4. Goedel's second theorem
  • 6. Around Goedel's theorem

  • 6.1. Methodological consequences
  • 6.2. Double incompleteness theorem
  • 6.3. Is mathematics "creative"?
  • 6.4. On the size of proofs
  • 6.5. Diophantine incompleteness theorem: natural numbers evolving?
  • 6.6. Loeb's theorem
  • 6.7. Consistent universal statements are provable
  • 6.8. Berry's paradox and incompleteness. Chaitin's theorem
  • 7. References

    Appendix 1. About model theory

    Appendix 2. Around Ramsey's theorem

     

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    what is mathematics, logic, mathematics, foundations, incompleteness theorem, mathematical, Gödel, Godel, book, Goedel, tutorial, textbook, methodology, philosophy, nature, theory, formal, axiom, theorem, incompleteness, online, web, free, download, teaching, learning, study, student, Podnieks, Karlis