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"Formalizing 100 Theorems" by Freek Wiedijk lists 100 mathematical theorems and the various systems that have formalized a nontrivial number of them. This list is discussed in "Formal Proof - Getting Started" (Freek Wiedijk, Notices of the AMS, Volume 55, Number 11, December 2008). Rightly or wrongly, this list is used by others to judge proof systems. Wiedijk's "getting started" picks as its primary examples HOL Light and Mizar, which at the time had the largest number of proofs. Similarly, "Case Studies in Proof Checking" by Robert C. Kam says, "Judging by Dr. Wiedijk's Formalizing 100 Theorems list, which gives an overview of the headway various proof systems have made in mathematics, Coq and Mizar are two of the most successful systems in use today (Wiedijk, 2007)".

Currently there are **72** proofs proven by Metamath from this list of
100. As of 2019-11-25 this number of proofs is more than
Coq (69), Mizar (69),
ProofPower (43), Lean (29),
nqthm/ACL2 (18), PVS (17), and NuPRL/MetaPRL (8);
it is short of only Isabelle (82) and HOL Light (86).
This is very good, especially considering that there had been no significant
effort until 2014 to prove theorems from this list of 100.
In this page, you can see the
completed Metamath proofs and the
Metamath proofs to be done from this list of
metamath proofs.
Some graphs showing Metamath 100 progress are available (click the
Authors tab for a pie chart).

Like all Metamath proofs, all reasoning is done directly in the
proof itself rather than by algorithms embedded in the verification
program. As a result, the proofs are completely transparent with
nothing hidden from the user, and every step can be followed through a
hyperlink to its corresponding proof or definition.
Therefore, the Metamath Proof Explorer (MPE aka set.mm) database
is the *largest* database of formally-verified mathematics
that records every step of a proof by directly
referring to only an axiom or previous proof
(many competing databases listed above
only record tactics that record how to
rediscover the proof, instead of recording
the specific proven steps actually used in the proof).

The theorems in MPE are routinely verified by 5 different programs written in 5 different programming languages by more than 5 different people. This provides very strong justification in believing that the proofs are correct.

What's more, all of the proofs listed here are current and verified with the current versions of Metamath tools. This is not the case with some other systems, where older proofs have not always been kept synchronized with the current system and thus have become essentially lost.

Since the kernel of Metamath is extremely small and rarely changes, the underlying Metamath language (as implemented by over a dozen independently-written verifiers) is very stable over time and can be verified very rapidly. The entire content of set.mm set theory database can be verified in less than 5 sec with the metamath program and in 0.7 sec with a recent version of Stefan O'Rear's smm3 verifier that utilizes multiple CPU cores. As of June 2016, altogether the theorems listed here ultimately make use of 12151 of the 28366 theorems in set.mm for their full derivation from ZFC axioms. (This doesn't mean that 12151 theorems are dedicated to the theorems on this list. Most are library-type theorems shared by many other theorems; for example, many of the theorems on this list depend on the complex number construction, which itself involves 3014 theorems to derive starting from the ZFC axioms.)

Here is the list of the Metamath proofs that are available from this list of 100, along with credit to the individual(s) who created the Metamath formalization. Almost all of these proofs are from the Metamath Proof Explorer, aka database set.mm, which is based on classical logic. However, there are some proofs available in the Intuitionistic Logic Explorer, aka database iset.mm, which uses intuitionistic logic instead. Please email missing entries to Norm Megill! The intuitionistic logic explorer (iset.mm) database also includes finds and findes.

Note for potential
contributors: The development tools most people use, in addition to a
good text editor, are mmj2 (which has an
introductory video) and the metamath
program (which has a tutorial in Chapter 2 of the *Metamath* book). Most contributors
keep their work in progress in private sections of set.mm called
"mathboxes" to prevent interfering with others' work. Mathboxes can be
released via a GitHub pull
request and will later be moved to the main part of set.mm by its
maintainers as appropriate. Alternately, mathboxes can be emailed to
Norm. Requests for help on the Metamath Google Group
can help things go smoother. See the Most Recent Proofs page for recent
announcements.

- 1. The Irrationality of the Square Root of 2 (sqr2irr, by Norman Megill, 2001-08-20)
- 2. The Fundamental Theorem of Algebra (fta, by Mario Carneiro, 2014-09-15)
- 3. The Denumerability of the Rational Numbers (qnnen, revised by Mario Carneiro, 2013-03-03)
- 4. Pythagorean Theorem (pythi, by Norman Megill, 2008-04-17)
- 5. The Prime Number Theorem (pnt, by Mario Carneiro, 2016-06-01) - also see pnt2, pnt3
- 7. Law of Quadratic Reciprocity (lgsquad, by Mario Carneiro, 2015-06-19)
- 9. The Area of a Circle (areacirc, by Brendan Leahy, 2017-08-31)
- 10. Euler's Generalization of Fermat's Little Theorem (eulerth, by Mario Carneiro, 2014-02-28)
- 11. The Infinitude of Primes (infpn2, by Norman Megill, 2005-05-05)
- 14. Euler's Summation of 1 + (1/2)^2 + (1/3)^2 + .... (basel, by Mario Carneiro, 2014-07-30)
- 15. The Fundamental Theorem of Integral Calculus (ftc1 and ftc2, by Mario Carneiro, 2014-09-03)
- 17. De Moivre's Theorem (demoivreALT, by Steve Rodriguez, 2006-11-10). See also the later proof demoivre (by Norman Megill, 2007-07-24), which is shorter and more general but uses the exponential function.
- 18. Liouville's Theorem and the Construction of Transcendental Numbers (aaliou, by Stefan O'Rear, 2014-11-22)
- 19. Four Squares Theorem (4sq, by Mario Carneiro, 2014-07-16)
- 20. All Primes (1 mod 4) Equal the Sum of Two Squares (2sq, by Mario Carneiro, 2015-06-20)
- 22. The Non-Denumerability of the Continuum (ruc, by Norman Megill, 2004-08-13)
- 23. Formula for Pythagorean Triples (pythagtrip, by Scott Fenton, 2014-04-19)
- 25. Schroeder-Bernstein Theorem (sbth, by Norman Megill, 1998-06-08 revised 2007-01-20)
- 26. Leibniz' Series for Pi (leibpi, by Mario Carneiro, 2015-04-16)
- 27. Sum of the Angles of a Triangle (ang180, by Mario Carneiro, 2014-09-24)
- 30. The Ballot Problem (aka Bertrand's ballot problem) (ballotth, by Thierry Arnoux, contributed 2017-05-07)
- 31. Ramsey's Theorem (ramsey, by Mario Carneiro, 2015-04-23)
- 34. Divergence of the Harmonic Series (harmonic, by Mario Carneiro, 2014-07-11)
- 35. Taylor's Theorem (taylth, by Mario Carneiro, 2017-01-01)
- 37. The Solution of a Cubic (cubic, by Mario Carneiro, 2015-04-26)
- 38. Arithmetic Mean/Geometric Mean (amgm, by Mario Carneiro, 2015-06-21)
- 39. Solutions to Pell's Equation (rmxycomplete, by Stefan O'Rear, 2014-11-22)
- 42. Sum of the Reciprocals of the Triangular Numbers (trirecip, by Scott Fenton, 2014-05-02)
- 44. The Binomial Theorem (binom, Norman Megill, 2005-12-07)
- 45. The Partition Theorem (by Euler) (eulerpart, Thierry Arnoux, 2018-08-30)
- 46. The Solution of the General Quartic Equation (quart, by Mario Carneiro, 2015-05-06)
- 48. Dirichlet's Theorem (dirith, by Mario Carneiro, 2016-05-12)
- 49. The Cayley-Hamilton Theorem (cayleyhamilton, by Alexander van der Vekens, 2019-11-25)
- 51. Wilson's Theorem (wilth, by Mario Carneiro, 2015-01-28)
- 52. The Number of Subsets of a Set (pw2en, by Norman Megill, 2004-01-29)
- 54. The Konigsberg Bridge Problem (konigsberg, by Mario Carneiro, 2015-04-16)
- 55. Product of Segments of Chords (chordthm by David Moews, 2017-02-28)
- 57. Heron's Formula (heron by Mario Carneiro based on work by Jon Pennant and Thierry Arnoux, 2019-03-10)
- 58. Formula for the Number of Combinations (hashbc, by Mario Carneiro, 2014-07-13)
- 60. Bezout's Theorem (bezout, by Mario Carneiro, 2014-02-22)
- 61. Theorem of Ceva (cevath, by Saveliy Skresanov, 2017-09-24)
- 63. Cantor's Theorem (canth2, by Norman Megill, 1994-08-07)
- 64. L'Hôpital's Rule (lhop, by Mario Carneiro, 2016-12-30)
- 65. Isosceles Triangle Theorem (isosctr, by Saveliy Skresanov, 2017-01-01)
- 66. Sum of a Geometric Series (geoser, by Norman Megill, 2006-05-09)
- 68. Sum of an arithmetic series (arisum, by Frédéric Liné, 2006-11-16) - arisum is not fully general, but it would be straightforward to enhance.
- 69. Greatest Common Divisor Algorithm (eucalg, by Paul Chapman, 2011-03-31)
- 70. The Perfect Number Theorem (perfect, by Mario Carneiro, 2016-05-17)
- 71. Order of a Subgroup (lagsubg, by Mario Carneiro, 2014-07-11) - also see lagsubg2
- 72. Sylow's Theorem (sylow1 and sylow2 and sylow2b and sylow3, by Mario Carneiro, 2015-01-19)
- 73. Ascending or Descending Sequences (erdsze and erdsze2, by Mario Carneiro, 2015-01-28)
- 74. The Principle of Mathematical Induction (finds, by Norman Megill, 1995-04-14). There are many versions of Mathematical Induction in set.mm. Theorem findes (by Raph Levien, 9-Jul-2003) is a compact and more traditional-looking version with explicit substitution. Another alternative is nnind (by Norman Megill, 10-Jan-1997), which uses natural numbers instead of ordinal numbers and might be less obscure for non-mathematicians. The intuitionistic logic explorer (iset.mm) database also includes finds and findes.
- 75. The Mean Value Theorem (mvth, by Mario Carneiro, 2014-09-14)
- 77. Sum of kth powers (fsumkthpow, by Scott Fenton, 2014-05-16)
- 78. The Cauchy-Schwarz Inequality (sii, by Norman Megill, 2008-01-12) - note that this is also called "Schwarz" by some authors and "Bunjakovaskij-Cauchy-Schwarz" by others.
- 79. The Intermediate Value Theorem (ivth, by Paul Chapman, 2008-01-22)
- 80. Fundamental Theorem of Arithmetic (1arith2, by Paul Chapman, 2012-11-17)
- 81. Erdős's proof of the divergence of the inverse prime series (prmrec, by Mario Carneiro, 2014-08-10)
- 83. The Friendship Theorem (friendship, by Alexander van der Vekens, 2018-10-09)
- 85. Divisibility by 3 Rule (3dvds, by Mario Carneiro, 2014-07-14)
- 86. Lebesgue Measure and Integration (itgcl, by Mario Carneiro, 2014-06-29)
- 87. Desargues's Theorem (dath, by Norman Megill, 2012-08-20)
- 88. Derangements Formula (derangfmla and subfaclim, by Mario Carneiro, 2015-01-28)
- 89. The Factor and Remainder Theorems (facth and plyrem, by Mario Carneiro, 2014-07-26)
- 90. Stirling's Formula (stirling by Glauco Siliprandi, 2017-06-29)
- 91. The Triangle Inequality (abstrii, by Norman Megill, 1999-10-02)
- 93. The Birthday Problem (birthday, by Mario Carneiro, 2015-04-17)
- 94. The Law of Cosines (lawcos, by David A. Wheeler, 2015-06-12)
- 95. Ptolemy's Theorem (ptolemy, by David A. Wheeler, 2015-05-31)
- 96. Principle of Inclusion/Exclusion (incexc, by Mario Carneiro, 2017-08-07)
- 97. Cramer's Rule (cramer, by Alexander van der Vekens, 2019-02-21, which built on the key work on determinants by Stefan O'Rear)
- 98. Bertrand's Postulate (bpos, by Mario Carneiro, 2014-03-15)

The page "Formalizing 100 Theorems" also contains a supplementary list of "obvious omissions" from the 100. Of those, the following have been formalized:

- Every vector space is free (lbsex, by Mario Carneiro, 2014-06-25)
- Heine-Borel Theorem (heibor, by Jeff Madsen, 2009-09-02) - also see cnheibor
- Hilbert Basis Theorem (hbt, by Stefan O'Rear, 2015-04-04)
- Stone-Weierstrass Theorem (stowei, by Glauco Siliprandi, 2017-04-20)

These are all the theorems from the list of 100 that have **not** been formalized in Metamath. Please move these to the above list!

- 6. Gödel's Incompleteness Theorem
- 8. The Impossibility of Trisecting the Angle and Doubling the Cube
- 12. The Independence of the Parallel Postulate
- 13. Polyhedron Formula
- 16. Insolvability of General Higher Degree Equations
- 21. Green's Theorem
- 24. The Undecidability of the Continuum Hypothesis
- 28. Pascal's Hexagon Theorem
- 29. Feuerbach's Theorem
- 32. The Four Color Problem
- 33. Fermat's Last Theorem
- 36. Brouwer Fixed Point Theorem
- 40. Minkowski's Fundamental Theorem
- 41. Puiseux's Theorem
- 43. The Isoperimetric Theorem
- 47. The Central Limit Theorem
- 50. The Number of Platonic Solids
- 53.
*π*is Transcendental - 56. The Hermite-Lindemann Transcendence Theorem
- 59. The Laws of Large Numbers
- 62. Fair Games Theorem
- 67.
*e*is Transcendental - 76. Fourier Series
- 82. Dissection of Cubes (J.E. Littlewood's "elegant" proof)
- 84. Morley's Theorem
- 92. Pick's Theorem
- 99. Buffon Needle Problem
- 100. Descartes Rule of Signs

You can see other proofs done with Metamath and for traditional mathematics on the Metamath Proof Explorer Home Page. Note that there are pages similar to this one for other tools, such as these pages on HOL and Mizar.

This metamath list was originally developed by David A. Wheeler and Norman Megill. If you add new theorems to the list, please tell Freek Wiedijk (freek at cs dot ru dot nl)

This page is dedicated to the public domain through the Creative Commons license CC0, to maximize the availability of this page's information.

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