# Talk:Chain duality III (Ex)

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Line 16: | Line 16: | ||

FT^2M\ar[r]^{Fe_M}& | FT^2M\ar[r]^{Fe_M}& | ||

F(M) | F(M) | ||

− | } | + | }$$ |

− | + | as the first square commutes by naturality of $G$ and the second one by definition of a | |

+ | functor of categories with chain duality. | ||

</wikitex> | </wikitex> |

## Revision as of 11:34, 1 June 2012

We check this for objects .

Let be an element of .

We have to check the equality of

and

This follows from the commutative diagram

as the first square commutes by naturality of and the second one by definition of a functor of categories with chain duality.