Xah Talk Show 2019-04-26, history of Wolfram MathWorld, Stereographic Projection, Category Theory?

topic/links mentioned:

• history of Wolfram MathWorld http://mathworld.wolfram.com/MoebiusTransformation.html
• xah lee review on The CRC Concise Encyclopedia of Mathematics by Eric W. Weisstein [ https://www.amazon.com/CRC-Concise-Encyclopedia-Mathematics/product-reviews/0849396409?pageNumber=2 ]
• Geometric Inversion
• Stereographic Projection
• Stereographic Projection 3D-Printed Physical Model
• Stereographic projection
• Möbius transformation
• Riemann sphere
• Pop Mechanics Mag, Pop Science Mag, OMNI Mag
• Free Math Textbooks
• Real analysis
• https://mathoverflow.net/