Ejemplo n.º 1
0
    def __init__(self, X, Y, category=None, check=True, base=ZZ):
        """
        The Python constructor.

        INPUT:

        The same as for any homset, see
        :mod:`~sage.categories.homset`.

        EXAMPLES::

            sage: P1xP1 = toric_varieties.P1xP1()
            sage: P1 = toric_varieties.P1()
            sage: hom_set = P1xP1.Hom(P1);  hom_set
            Set of morphisms
              From: 2-d CPR-Fano toric variety covered by 4 affine patches
              To:   1-d CPR-Fano toric variety covered by 2 affine patches
            
        An integral matrix defines a fan morphism, since we think of
        the matrix as a linear map on the toric lattice. This is why
        we need to ``register_conversion`` in the constructor
        below. The result is::

            sage: hom_set(matrix([[1],[0]]))
            Scheme morphism:
              From: 2-d CPR-Fano toric variety covered by 4 affine patches
              To:   1-d CPR-Fano toric variety covered by 2 affine patches
              Defn: Defined by sending Rational polyhedral fan in 2-d lattice N
                    to Rational polyhedral fan in 1-d lattice N.
        """
        SchemeHomset_generic.__init__(self, X, Y, category=category, check=check, base=base)
        self.register_conversion(MatrixSpace(ZZ, X.fan().dim(), Y.fan().dim()))
Ejemplo n.º 2
0
    def __init__(self, X, Y, category=None, check=True, base=ZZ):
        """
        The Python constructor.

        INPUT:

        The same as for any homset, see
        :mod:`~sage.categories.homset`.

        EXAMPLES::

            sage: P1xP1 = toric_varieties.P1xP1()
            sage: P1 = toric_varieties.P1()
            sage: hom_set = P1xP1.Hom(P1);  hom_set
            Set of morphisms
              From: 2-d CPR-Fano toric variety covered by 4 affine patches
              To:   1-d CPR-Fano toric variety covered by 2 affine patches

        An integral matrix defines a fan morphism, since we think of
        the matrix as a linear map on the toric lattice. This is why
        we need to ``register_conversion`` in the constructor
        below. The result is::

            sage: hom_set(matrix([[1],[0]]))
            Scheme morphism:
              From: 2-d CPR-Fano toric variety covered by 4 affine patches
              To:   1-d CPR-Fano toric variety covered by 2 affine patches
              Defn: Defined by sending Rational polyhedral fan in 2-d lattice N
                    to Rational polyhedral fan in 1-d lattice N.
        """
        SchemeHomset_generic.__init__(self, X, Y, category=category, check=check, base=base)
        self.register_conversion(MatrixSpace(ZZ, X.fan().dim(), Y.fan().dim()))
Ejemplo n.º 3
0
 def __init__(self, X, S):
     R = X.base_ring()
     SchemeHomset_generic.__init__(self, spec.Spec(S, R), X)
     P2 = X.curve()._printing_ring
     if S != R:
         y = str(P2.gen())
         x = str(P2.base_ring().gen())
         P1 = PolynomialRing(S,name=x)
         P2 = PolynomialRing(P1,name=y)
     self._printing_ring = P2
Ejemplo n.º 4
0
 def __init__(self, X, S):
     R = X.base_ring()
     SchemeHomset_generic.__init__(self, spec.Spec(S, R), X)
     P2 = X.curve()._printing_ring
     if S != R:
         y = str(P2.gen())
         x = str(P2.base_ring().gen())
         P1 = PolynomialRing(S, name=x)
         P2 = PolynomialRing(P1, name=y)
     self._printing_ring = P2