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fixed A-infinity to E-infinity
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Mike Shulman
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$Ho(C^T)$ is almost never monadic over $Ho(C)$. The objects of $Ho(C^T)$ are $T$-algebras in $C$, which means in particular that their $T$-algebra structure commutes strictly, whereas the algebras for the induced monad on $Ho(C)$ will only have algebra structure commuting up to (non-specified, non-coherent) isomorphism.

For instance, I believe that if $T$ is the monad derived from an $A_\infty$$E_\infty$-operad, then $T$-algebras are $A_\infty$$E_\infty$-spaces, whereas $Ho(T)$-algebras are "$H_\infty$-spaces". These have an obstruction theory specifying when they can be $A_\infty$$E_\infty$-ized. (Anyone who is more familiar with the exact meaning of $H_\infty$, feel free to chime in.)

$Ho(C^T)$ is almost never monadic over $Ho(C)$. The objects of $Ho(C^T)$ are $T$-algebras in $C$, which means in particular that their $T$-algebra structure commutes strictly, whereas the algebras for the induced monad on $Ho(C)$ will only have algebra structure commuting up to (non-specified, non-coherent) isomorphism.

For instance, I believe that if $T$ is the monad derived from an $A_\infty$-operad, then $T$-algebras are $A_\infty$-spaces, whereas $Ho(T)$-algebras are "$H_\infty$-spaces". These have an obstruction theory specifying when they can be $A_\infty$-ized. (Anyone who is more familiar with the exact meaning of $H_\infty$, feel free to chime in.)

$Ho(C^T)$ is almost never monadic over $Ho(C)$. The objects of $Ho(C^T)$ are $T$-algebras in $C$, which means in particular that their $T$-algebra structure commutes strictly, whereas the algebras for the induced monad on $Ho(C)$ will only have algebra structure commuting up to (non-specified, non-coherent) isomorphism.

For instance, if $T$ is the monad derived from an $E_\infty$-operad, then $T$-algebras are $E_\infty$-spaces, whereas $Ho(T)$-algebras are "$H_\infty$-spaces". These have an obstruction theory specifying when they can be $E_\infty$-ized.

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Mike Shulman
  • 66.8k
  • 7
  • 162
  • 368

$Ho(C^T)$ is almost never monadic over $Ho(C)$. The objects of $Ho(C^T)$ are $T$-algebras in $C$, which means in particular that their $T$-algebra structure commutes strictly, whereas the algebras for the induced monad on $Ho(C)$ will only have algebra structure commuting up to (non-specified, non-coherent) isomorphism.

For instance, I believe that if $T$ is the monad derived from an $A_\infty$-operad, then $T$-algebras are $A_\infty$-spaces, whereas $Ho(T)$-algebras are "$H_\infty$-spaces". These have an obstruction theory specifying when they can be $A_\infty$-ized. (Anyone who is more familiar with the exact meaning of $H_\infty$, feel free to chime in.)