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A capital H with a raised degree, the dual of homology.
Also known as: Cohomology group, H superscript n, Singular cohomology notation
Cohomology is written with the degree raised rather than lowered, and that single typographic difference is the whole distinction from homology in notation. Cohomology carries a product structure that homology does not, which is why it is preferred despite being harder to define.
Denotes the cohomology groups of a space, indexed by a raised degree.
Contexts: Mathematics
Is distinguished from homology in writing solely by the superscript position of the degree.
Contexts: Mathematics
Carries a cup product making it a ring, which homology lacks and which is the main reason to use it.
Contexts: Mathematics
A capital letter H with a small numeral raised to its upper right, followed by a bracketed space name.