Hesse pencil
In mathematics, the syzygetic pencil or Hesse pencil, named for Otto Hesse, is a pencil (one-dimensional family) of cubic plane elliptic curves in the complex projective plane, defined by the equation
Each curve in the family is determined by a pair of parameter values () (not both zero) and consists of the points in the plane whose homogeneous coordinates
satisfy the equation for those parameters. Multiplying both
and
by the same scalar does not change the curve, so there is only one degree of freedom in selecting a curve from the pencil, but the two-parameter form given above allows either
or
(but not both) to be set to zero.