Rational principal-parts resolution on an algebraic curve

ID: rational-principal-parts-resolution-on-an-algebraic-curve

On an irreducible algebraic curve, let be the constant rational-section sheaf and put . Every open subset is quasi-compact, so compatible finite-support families glue with finite support. Its stalk at is the displayed rational-principal-part quotient. A rational section is regular outside finitely many points, making its principal-part map well defined. The resulting sequence is stalkwise exact. Both right-hand sheaves are flasque, and consequently is the cokernel of the global principal-part map and for . The curve and Zariski-topology hypotheses distinguish finite support here from locally finite pole sets in complex analysis.

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