Multivariate Polynomials over Rational Function Fields

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When I try this, the error I get is a little more informative:

sage: I2 = I.elimination_ideal([x])
...
TypeError: Cannot call Singular function 'eliminate' with ring parameter of type 
'<class 'sage.rings.polynomial.multi_polynomial_ring.MPolynomialRing_polydict_domain'>'

The function eliminte comes from

sage: eliminate = sage.libs.singular.ff.eliminate

which is a wrapper for the Singular function and is supposed to convert Sage's rings to rings that Singular understands . . . however it seems that this wrapper does not understand the _polydict_domain rings. Perhaps one could convert R to a ring that the wrapper does understand (or file this as a bug in the wrapper and fix it). Checking, I see that there is a ring type MPolynomialRing_libsingular, but it only allows base rings from a very small list (like ZZ and finite fields).

Maybe someone who knows more about the Singular interface can help here?

Make u and v be in the Fraction field:

sage: B.<u,v> = Frac(QQ['u,v'])
sage: R.<x,y> = PolynomialRing(B, 'x', 'y')
sage: I = R.ideal(v * x^2 + y, u* x * y + y^2) 
sage: g = I.groebner_basis()
sage: g
[y^3 + u^2/v*y^2, x^2 + 1/v*y, x*y + 1/u*y^2]