In a strange sense, an admission of the arbitrary frailties of psychiatry. This was an attempt to 'standardize' descriptive diagnosis of syndromes and conditions, because shrinks basically diagnosed in haphazard ad hoc ways. Shrinks from different countries used different labels i.e. some called certain kind of manic depression schizophrenia, some called certain schizophrenia manic depression etc. They didn't agree so they had to create a system.
@Patrick business 'calculus' for determining investment decisions.
In reality, linear algebraic expression they call 'calculus' in order to pitch BS for a business degree vs BA.
In this case, American Eagle's Sweeney Ad is a good pay off with Gen Z. Not just to Gen Z males, but also Gen Z females who will now buy the jeans to attract the males. Company's stock rose 10% after release of that ad.
That meme is a poke in the Left's eye with Trump's cock. Or, may as well be. Especially the college grads who are 'smarter' than the rest of MAGA males. Many will recognize the formula even though only about 10% actually learned it/90% cheated on the exam.
#humor