# On the exponential solution of differential equations for a linear operator

@article{Magnus1954OnTE, title={On the exponential solution of differential equations for a linear operator}, author={Wilhelm Magnus}, journal={Communications on Pure and Applied Mathematics}, year={1954}, volume={7}, pages={649-673} }

The present investigation was stimulated by a recent paper of K. 0. Friedrichs 113, who arrived at some purely algebraic problems in connection with the theory of linear operators in quantum mechanics. In particuIar, Friedrichs used a theorem by which the Lie elements in a free associative ring can be characterized. This theorem is proved in Section I1 of the present paper together with some applications which concern the addition theorem of the exponential function for non-commuting variables… Expand

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