Archive

28 problems

#	Problem	Type	Date	✓
28	Fundamental Group of the Circle Is ℤ	topology	2026-05-05	○
27	Integral of a Max with a Circle	Integration	2026-04-25	○
26	Dini's Theorem: When Pointwise Becomes Uniform	analysis	2026-04-25	○
25	An Impossible Integer Polynomial	Putnam	2026-04-24	○
24	Entire Function with Non-Negative Real Part	Complex Analysis	2026-04-23	○
23	The Topologist's Sine Curve	topology	2026-04-21	○
22	The Cantor Set: Measure Zero yet Uncountable	analysis	2026-04-20	○
21	Why LASSO Gives Sparsity but Ridge Does Not	ML/Stats	2026-04-19	○
20	Continuous but Nowhere Differentiable	analysis	2026-04-06	○
19	Integral of (x-1)²/(2eˣ+x²+1)	Integration	2026-04-04	○
18	Consecutive Subsum Divisible by n	Putnam	2026-04-03	○
17	Orthogonality to All Monomials Forces Zero	analysis	2026-03-30	○
16	Stein's Paradox	ML/Stats	2026-03-29	○
15	Integral of x² sin(x)	Integration	2026-03-28	○
14	No Function with f(f(n)) = n + 2025	Putnam	2026-03-27	○
13	Truncated Exponential Has No Repeated Roots	Putnam	2026-03-27	○
12	FTA via Liouville's Theorem	Complex Analysis	2026-03-26	○
11	Curvature of an Embedded Torus	Differential Geometry	2026-03-26	○
10	The Hat Check Problem	Probability	2026-03-25	○
9	Bertrand's Chord Paradox	Probability	2026-03-24	○
8	Integral of a Geometric Series	Integration	2026-03-14	○
7	Polynomial with No Integer Roots	Putnam	2026-03-13	○
6	Harmonic Series Is Never an Integer	Putnam	2026-03-13	○
5	The Schwarz Lemma	Complex Analysis	2026-03-12	○
4	Parallel Transport on a Sphere	Differential Geometry	2026-03-12	○
3	Expected Number of Records	Probability	2026-03-11	○
2	Bertrand's Ballot Problem	Probability	2026-03-11	○
1	Lp Norm → L∞	analysis	2026-03-09	○