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The Stacks project

  • if $0 \to K \to L \to M \to 0$ is a short exact sequence of $R$-modules and $K$, $M$ are free, then $L$ is free,


Comments (1)

Comment #10739 by on

Interesting lemma. The assumption that both and are free -modules makes it tempting to conclude that is also free—but as always, module theory loves subtlety. Curious how the structure of itself might affect this.

Regard Alysnes


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