On some mathematical topics I found interesting.
Another application of Baire category theorem
Not all finitely-presented groups are fundamental groups of closed 3-manifolds
How Stallings proved finitely generated groups are subgroup separable
Free groups acting on the circle
Third Homotopy Group of the Sphere and Hopf Fibration
Hairy ball theorem without degree theory
Number of group topologies on the real line
Almost all matrices are diagonalizable
Some surprising but elementary facts in infinite-dimensional topology
« Older posts
Exploring the works of Gilbert Baumslag
Gödel Lost Lettre and P=NP
Geometric Group Theory
Geometry and the Imagination
Here there be dragons
Image des Mathématiques
Low Dimensional Topology
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