what concepts are the most difficult to master? Links to Wikipedia are welcome.
Bistromathics, see Hitch Hiker’s Guide to the Galaxy. Jocularity aside, Fermat’s Last Theorem, others to follow.
The Quintic Equation
Information Theory and how it relates to Bioinformatics and Linguistics.
Chaos Theory and especially its relation to biology.
Game Theory and how it relates to cultural and biological intelligent evolutions.
Dimension Theory and how it relates to Carl Sagan depiction of 4th and 5th Dimension concepts… and yes, Spiritual archetypes and Platonic forms.
Agree with the above.
But for me, counting on 18 toes.
See!! Pachyderm has stated a corollary for a postulate of Bistromathics. French bistro waiters never count the same things the same way, even twice. Pace Heraclitus & Parmenides.
Number theory.