Derived functor
introduction
- basic tool to define cohomology theory
- extend a left invariant functor to get a derived functor
- then we get a cohomology theory
- e.g. sheaf cohomology of a topological space X with coefficients in a sheaf \(\mathcal F\) = the right derived functor of the global section functor
left invariant functors
global section functor
- a functor from sheaves on \(X\) to abelian groups defined by
\[ \mathcal F \mapsto H^{0}(X, \mathcal F) \]
invariants
- \(G\) : group
- from modules of \(G\) to abelian groups
\[ M\mapsto M^{G} \]
메타데이터
위키데이터
- ID : Q320245