Diagram Lemma

Any lemma on commutative diagrams. It can give relations between maps (as in the five lemma) or tell how to construct new diagrams from old ones (as in the snake lemma).

See also

Commutative Diagram, Diagram Chasing, Four Lemma, Five Lemma, Nine Lemma, Snake Lemma, Zig-Zag Lemma

This entry contributed by Margherita Barile

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References

Mac Lane, S. "Diagram Lemmas." Ch. 7.4 in Categories for the Working Mathematician. New York: Springer-Verlag, pp. 198-205, 1971.

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Diagram Lemma

Cite this as:

Barile, Margherita. "Diagram Lemma." From MathWorld--A Wolfram Resource, created by Eric W. Weisstein. https://mathworld.wolfram.com/DiagramLemma.html

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