The Jacobian group of a one-dimensional linear series is given by intersections of the base curve with the Jacobian curve of itself and two curves cutting the series.
Jacobian Group
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References
Coolidge, J. L. A Treatise on Algebraic Plane Curves. New York: Dover, p. 283, 1959.Referenced on Wolfram|Alpha
Jacobian GroupCite this as:
Weisstein, Eric W. "Jacobian Group." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/JacobianGroup.html