morphism : an abelian morphism is a morphism from a group G to an abelian
square : the absolute square of a complex number z = x +
iy, with x and y reals, is the number |x + iy|² = x² + y².
: the Adams'circle
of a triangle ABC is the circle passing by the 6 points, M,N,O,P,Q and R
of intersection of the lines parallel to the sides of the contact triangle from the Gergonne point with the sides of ABC.
variety : an affine algebraic set V
is called an affine variety if the ideal I(V) is a prime ideal in .
algebraic set defined over K : let
K be a perfect field,
an affine algebraic set V is defined over K if the ideal I(V) can be generated by polynomials in K[X].
coordinate ring of K/V : let K be a
perfect field and
let V/K be a variety defined over K the affine coordinate
ring of K/V
is the integral
domain K[V] defined by : K[V] = K[X]/I(V/K) with I(V/K) = I(V) Ç K[X].