217 - MITTAG-LEFFLER, Gösta. On the Analytical Representation of Integrals and Invariants. From a Linear and Homogeneous Differential Equation.

MITTAG-LEFFLER, Gösta. On the Analytical Representation of Integrals and Invariants. From a Linear and Homogeneous Differential Equation. The great Swedish mathematician’s personal copy of this rare offprint in its original binding. Sl., n.p. [journal Acta Mathematica], n.d. [1891]. In-4, red half-maroquin with corner pieces, smooth spine adorned with the title running lengthwise, original blue covers preserved, red head. 32 pp. Minor scuffing and stains on the binding. A rare offprint of this paper by the Swedish mathematician Gösta Mittag-Leffler (1846–1927), founder of the prestigious journal *Acta Mathematica*. Published as the opening article of Volume 15 of the journal, this text marks a major advance in the wake of Henri Poincaré’s work on complex analysis and the global study of differential equations. In it, Mittag-Leffler develops new methods of analytic representation that would profoundly influence mathematical physics and the calculation of invariants at the turn of the 20th century. The author’s personal copy bears his beautiful bookplate featuring the Latin motto “Sibi et amicis” (for oneself and for one’s friends) and adorned with an owl—a symbol of wisdom—peering down at a book titled “Acta Mathematica.” In fine condition and in a contemporary binding.