Chit-chat on Lagrange's four-square theorem

Lagrange’s four-square theorem is a beautiful result in number theory. However, to the best of my knowledge, I haven’t encountered it often in theoretical computer science. Today’s entry discusses two interesting stories related to this theorem.

Xena Mathematicians learning Lean by doing.

Lagrange's Four-Square Theorem Seen Using Polygons and Lines - Wolfram Demonstrations Project

SOLVED: 8.35 (Lagrange's Four-Square Theorem) If n is a natural number, it can be expressed as the sum of four squares. A lattice in 4-space is a set of the form (x,y,z,w)

Chit-chat on Lagrange's four-square theorem

Lagrange's four-square theorem - Wikipedia

Differential Equations - Laplace's Equation

Original as single pages corrected - LaGrange College

Proofs of Impossibility

History of mathematics

Student Posters for Sale

Sum of squares, Part-2, Sum of four squares