Естественно, не могло обойтись без юмора. На скриншоте — сноска на странице 2 книги Ian G. Macdonald-а "Symmetric Functions and Hall Polynomials":
"Some authors (especially Francophones) prefer the convention of coordinate geometry (in which the first coordinate increases from left to right and the second coordinate from bottom to top) and define the diagram of λ to be the set of (i,j) \in Z^2 such that 1 \le i \le λ_j. Readers who prefer this convention should read this book upside down in a mirror."