Proof Gallery

• Computing Percentages Easier
  September 5, 2023
• A parlor trick for SET
  March 25, 2018
• A Spectral Analysis of Moore Graphs
  November 3, 2016
• Methods of Proof — Diagonalization
  June 8, 2015
• Learning a single-variable polynomial, or the power of adaptive queries
  November 18, 2014
• A Rook Game
  August 31, 2014
• Cauchy-Schwarz Inequality (and Amplification)
  July 23, 2013
• Ramsey Number Lower Bound
  December 2, 2012
• There are Infinitely Many Primes (Erdős)
  November 10, 2012
• Double Angle Trigonometric Formulas
  May 19, 2012
• False Proof – 2 = 4, As the Limit of an Infinite Power Tower
  May 5, 2012
• Classic Nintendo Games are NP-Hard
  March 22, 2012
• Fundamental Theorem of Algebra (With Picard's Little Theorem)
  February 7, 2012
• The Fundamental Theorem of Algebra (with Galois Theory)
  February 2, 2012
• Handshake Lemma
  January 29, 2012
• The Fundamental Theorem of Algebra (with the Fundamental Group)
  January 22, 2012
• The Fundamental Theorem of Algebra (with Liouville)
  January 17, 2012
• Tiling a Chessboard with Dominoes (Opposite Colors Removed)
  November 18, 2011
• Z[√2] has Infinitely Many Units
  November 7, 2011
• False Proof: 1 = 2 (with Calculus)
  October 25, 2011
• The Smallest Non-Cyclic Simple Group has Order 60
  October 8, 2011
• N Choose 2 is the Sum of the First N-1 Integers
  October 2, 2011
• n-Colorability is Equivalent to Finite n-Colorability (A Formal Logic Proof)
  September 4, 2011
• The Square Root of 2 is Irrational (Geometric Proof)
  August 14, 2011
• False Proof—All Numbers are Describable in at Most Twenty Words
  July 28, 2011
• Möbius Transformations are Isometries of a Sphere
  July 23, 2011
• False Proof—The Reals are Countable
  July 19, 2011
• False Proof—All Horses are the Same Color
  July 16, 2011
• Three Circles and Collinear Centers of Dilation
  July 13, 2011
• False Proof—31.5 = 32.5
  July 7, 2011
• False Proof—There are Finitely Many Primes
  July 5, 2011
• False Proof—1 = 2
  July 5, 2011
• Geometric Series with Geometric Proofs
  July 5, 2011
• Sums of k Powers
  July 1, 2011
• Tiling a Chessboard
  June 26, 2011
• Area of a Triangle
  June 24, 2011
• Sums of the first n numbers, squares
  June 24, 2011
• The Party Problem
  June 23, 2011
• Number of Games in a Tournament
  June 23, 2011