Definition
See also: Definition of homologyFor a topological space X, the cohomology group Hn(X;G), with coefficients in G, is defined to be the quotient Ker(δn)/Im(δn-1) at Cn(X;G) in the cochain complex
Elements in Ker(δn) are n-cocycles and elements in Im(δn-1) are n-coboundaries. The cohomology groups with n ≥ 1 are called the higher cohomology.
Read more about this topic: Cohomology
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