The Foundation of Modern Math which is based on the “Set Theory”, hit a crisis due to Bertrand Russell “Barber’s Paradox”, until the Zermelo-Fraenkel Axioms came to its rescue.
Here is a humorous example of an ISP Internet Plan violating the 9 Z-F Axioms:
How ISPs Violate the Laws of Mathematics:
Video:
Singapore Maths Tuition 