The cohomology of a chain complex C^*: H^n = ker d^n / im d^{n−1}. Dual to homology; carries a cup-product ring structure and often better computational properties.
The cohomology of a chain complex C^*: H^n = ker d^n / im d^{n−1}. Dual to homology; carries a cup-product ring structure and often better computational properties.