Definition 13.14.2. Assumptions and notation as in Situation 13.14.1. Let X \in \mathop{\mathrm{Ob}}\nolimits (\mathcal{D}).
we say the right derived functor RF is defined at X if the ind-object
(X/S) \longrightarrow \mathcal{D}', \quad (s : X \to X') \longmapsto F(X')is essentially constant1; in this case the value Y in \mathcal{D}' is called the value of RF at X.
we say the left derived functor LF is defined at X if the pro-object
(S/X) \longrightarrow \mathcal{D}', \quad (s: X' \to X) \longmapsto F(X')is essentially constant; in this case the value Y in \mathcal{D}' is called the value of LF at X.
By abuse of notation we often denote the values simply RF(X) or LF(X).
Comments (1)
Comment #9769 by Elías Guisado on
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