Sophus Lie, the mathematician

and analysed it is hard to do so in. a small space without creating animpression which would be misleading. Lie was also rather possessiveof his own work, sometimes unwilling in his exposition to adopt simplificationspublished by others and yet eager for recognition of it byothers. After only three years 1873-76 of his work on transformationgroups he is complaining of lack of interest of the mathematical publicand as a result turns to other topics (In comparison one might mentionElie Cartan who worked on Lie algebras for 25 years without much participationfrom anyone; it did not seem to bother him). But if someonedecided to publish research in transformation group theory then thatperson was well-advised to show his familiarity with Lie's papers. Evena colleague like Friedrich Schur, who made substantial improvements inthe proofs of the fundamental theorems was thus taken to task in print.The mathematician whose work always met with Lie's approval andadmiration was Elie Cartan. Let me therefore conclude with Cartan'swords spoken on the centenary of Lie's birth (cf. [8]):"Sophus Lie was of tall stature and had the classic Nordicappearance. A full blond beard framed his face and hisgray-blue eyes sparkled behind his eyeglasses. He gave theimpression of unusual physical strength. One always immediatelyfelt at ease with him, certain beforehand of hissincerity and his loyalty. He was not afraid to admit hisignorance of branches of mathematics unfamiliar to him,which nevertheless did not keep him from being aware ofhis own worth ...... Posterity will see in him the genius whocreated the theory of transformation groups, and we Frenchshall never be able to forget the ties which bind us to himand which make his memory dear to us".References[1] Anderson, I. M., Kamran, N., and Olver, P. J.. Internal, external andgeneralized symmetries. Advan. Math. 100 (1993), 53-100.[2] Blaschke, W., Vorlesungen fiber Differential Geometrie. Vol. I-III.Springer, Berlin, 1929.[3] Bluman, G. W., and Kumei, S., Symmetries and Differential Equations.Springer-Verlag, New York, 1989.j9