 ##  [Cochain Complex](/cochain-complex) 

  ##  [Cochain Complex](https://mathlogic.quantumdictionary.io/cochain-complex-0) 

  
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- Natural &amp; Formal Sciences -

**Mathematics &amp; Logic Dictionary**

 
Definition

A graded sequence of cochain groups or modules C^n with coboundary maps δ^n: C^n → C^{n+1} satisfying δ^{n+1} ∘ δ^n = 0; its cohomology H^n = ker δ^n / im δ^{n-1} measures obstructions dual to chain homology.