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localRingValuation -- The valuation defined by a local ring.

Synopsis

Description

This function constructs a valuation which returns the largest power of the maximal ideal of R that contains the input to the valuation.

i1 : R = QQ[x,y];
i2 : I = ideal(x,y);

o2 : Ideal of R
i3 : S = R_I

o3 = S

o3 : LocalRing, maximal ideal (x, y)
i4 : localVal = localRingValuation(S)

o4 = valuation from S to ZZ

o4 : Valuation
i5 : localVal(1 + x + y)

o5 = 0
i6 : localVal(x^4 + x^2*y^2 + x^7 + y^3)

o6 = 3
i7 : localVal(x^2 + x*y + y^2)

o7 = 2

This valuation may be applied to elements of the fraction field of R, where the value of the valuation is the difference between the valuations of the numerator and denominator.

i8 : localVal(1/(x^2+x*y+y^3))

o8 = -2

See also

Ways to use localRingValuation :

For the programmer

The object localRingValuation is a method function.