Can we “integrate” functors?

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Let $F:mathcalCrightarrow mathcalC'$ be a functor between "nice" (e.g. abelian with enough injectives) categories. If F is not exact we can form the derived functors $F',F'',...$
Is it possible to reverse this process ("integrate" $F$) or stated reversely: Are there nice conditions on a functor $F$ to be a derived functor?







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  • Yoneda observed that $L_p(F)(A) = textNat(textExt^p(texthom_A), F)$, this might be helpful.
    – Ivan Di Liberti
    Jul 16 at 15:34











  • Could you explain what $L_p$ is? And do you mean $textExt^p(texthom_A)$ to be $Ext^p(underline ,A)$?
    – Takirion
    Jul 17 at 8:34











  • @Takirion, I guess in this context $L_p$ is the left derivation of functors (see Wikipedia). So $L_p(F)$ is the derived functor, which you can apply to an object A.
    – Babelfish
    Jul 23 at 16:40











  • Ah, yes, this seems plausible.
    – Takirion
    Jul 23 at 17:17














up vote
9
down vote

favorite
7












Let $F:mathcalCrightarrow mathcalC'$ be a functor between "nice" (e.g. abelian with enough injectives) categories. If F is not exact we can form the derived functors $F',F'',...$
Is it possible to reverse this process ("integrate" $F$) or stated reversely: Are there nice conditions on a functor $F$ to be a derived functor?







share|cite|improve this question



















  • Yoneda observed that $L_p(F)(A) = textNat(textExt^p(texthom_A), F)$, this might be helpful.
    – Ivan Di Liberti
    Jul 16 at 15:34











  • Could you explain what $L_p$ is? And do you mean $textExt^p(texthom_A)$ to be $Ext^p(underline ,A)$?
    – Takirion
    Jul 17 at 8:34











  • @Takirion, I guess in this context $L_p$ is the left derivation of functors (see Wikipedia). So $L_p(F)$ is the derived functor, which you can apply to an object A.
    – Babelfish
    Jul 23 at 16:40











  • Ah, yes, this seems plausible.
    – Takirion
    Jul 23 at 17:17












up vote
9
down vote

favorite
7









up vote
9
down vote

favorite
7






7





Let $F:mathcalCrightarrow mathcalC'$ be a functor between "nice" (e.g. abelian with enough injectives) categories. If F is not exact we can form the derived functors $F',F'',...$
Is it possible to reverse this process ("integrate" $F$) or stated reversely: Are there nice conditions on a functor $F$ to be a derived functor?







share|cite|improve this question











Let $F:mathcalCrightarrow mathcalC'$ be a functor between "nice" (e.g. abelian with enough injectives) categories. If F is not exact we can form the derived functors $F',F'',...$
Is it possible to reverse this process ("integrate" $F$) or stated reversely: Are there nice conditions on a functor $F$ to be a derived functor?









share|cite|improve this question










share|cite|improve this question




share|cite|improve this question









asked Jul 16 at 14:00









Takirion

661211




661211











  • Yoneda observed that $L_p(F)(A) = textNat(textExt^p(texthom_A), F)$, this might be helpful.
    – Ivan Di Liberti
    Jul 16 at 15:34











  • Could you explain what $L_p$ is? And do you mean $textExt^p(texthom_A)$ to be $Ext^p(underline ,A)$?
    – Takirion
    Jul 17 at 8:34











  • @Takirion, I guess in this context $L_p$ is the left derivation of functors (see Wikipedia). So $L_p(F)$ is the derived functor, which you can apply to an object A.
    – Babelfish
    Jul 23 at 16:40











  • Ah, yes, this seems plausible.
    – Takirion
    Jul 23 at 17:17
















  • Yoneda observed that $L_p(F)(A) = textNat(textExt^p(texthom_A), F)$, this might be helpful.
    – Ivan Di Liberti
    Jul 16 at 15:34











  • Could you explain what $L_p$ is? And do you mean $textExt^p(texthom_A)$ to be $Ext^p(underline ,A)$?
    – Takirion
    Jul 17 at 8:34











  • @Takirion, I guess in this context $L_p$ is the left derivation of functors (see Wikipedia). So $L_p(F)$ is the derived functor, which you can apply to an object A.
    – Babelfish
    Jul 23 at 16:40











  • Ah, yes, this seems plausible.
    – Takirion
    Jul 23 at 17:17















Yoneda observed that $L_p(F)(A) = textNat(textExt^p(texthom_A), F)$, this might be helpful.
– Ivan Di Liberti
Jul 16 at 15:34





Yoneda observed that $L_p(F)(A) = textNat(textExt^p(texthom_A), F)$, this might be helpful.
– Ivan Di Liberti
Jul 16 at 15:34













Could you explain what $L_p$ is? And do you mean $textExt^p(texthom_A)$ to be $Ext^p(underline ,A)$?
– Takirion
Jul 17 at 8:34





Could you explain what $L_p$ is? And do you mean $textExt^p(texthom_A)$ to be $Ext^p(underline ,A)$?
– Takirion
Jul 17 at 8:34













@Takirion, I guess in this context $L_p$ is the left derivation of functors (see Wikipedia). So $L_p(F)$ is the derived functor, which you can apply to an object A.
– Babelfish
Jul 23 at 16:40





@Takirion, I guess in this context $L_p$ is the left derivation of functors (see Wikipedia). So $L_p(F)$ is the derived functor, which you can apply to an object A.
– Babelfish
Jul 23 at 16:40













Ah, yes, this seems plausible.
– Takirion
Jul 23 at 17:17




Ah, yes, this seems plausible.
– Takirion
Jul 23 at 17:17















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