Complete Discrete Valuation Rings (CDVR) and Fields (CDVF)¶

class sage.categories.complete_discrete_valuation.CompleteDiscreteValuationFields(s=None)

The category of complete discrete valuation fields

EXAMPLES:

sage: Zp(7) in CompleteDiscreteValuationFields()
False
sage: QQ in CompleteDiscreteValuationFields()
False
sage: LaurentSeriesRing(QQ,'u') in CompleteDiscreteValuationFields()
True
sage: Qp(7) in CompleteDiscreteValuationFields()
True
sage: TestSuite(CompleteDiscreteValuationFields()).run()

class ElementMethods
denominator()

Return the denominator of this element normalized as a power of the uniformizer

EXAMPLES:

sage: K = Qp(7)
sage: x = K(1/21)
sage: x.denominator()
7 + O(7^21)

sage: x = K(7)
sage: x.denominator()
1 + O(7^20)


Note that the denominator lives in the ring of integers:

sage: x.denominator().parent()
7-adic Ring with capped relative precision 20


An error is raised when the input is indistinguishable from 0:

sage: x = K(0,5); x
O(7^5)
sage: x.denominator()
Traceback (most recent call last):
...
ValueError: Cannot determine the denominator of an element indistinguishable from 0

valuation()

Return the valuation of this element.

EXAMPLES:

sage: K = Qp(7)
sage: x = K(7); x
7 + O(7^21)
sage: x.valuation()
1

super_categories()

EXAMPLES:

sage: CompleteDiscreteValuationFields().super_categories()
[Category of discrete valuation fields]

class sage.categories.complete_discrete_valuation.CompleteDiscreteValuationRings(s=None)

The category of complete discrete valuation rings

EXAMPLES:

sage: Zp(7) in CompleteDiscreteValuationRings()
True
sage: QQ in CompleteDiscreteValuationRings()
False
sage: QQ[['u']] in CompleteDiscreteValuationRings()
True
sage: Qp(7) in CompleteDiscreteValuationRings()
False
sage: TestSuite(CompleteDiscreteValuationRings()).run()

class ElementMethods
denominator()

Return the denominator of this element normalized as a power of the uniformizer

EXAMPLES:

sage: K = Qp(7)
sage: x = K(1/21)
sage: x.denominator()
7 + O(7^21)

sage: x = K(7)
sage: x.denominator()
1 + O(7^20)


Note that the denominator lives in the ring of integers:

sage: x.denominator().parent()
7-adic Ring with capped relative precision 20


An error is raised when the input is indistinguishable from 0:

sage: x = K(0,5); x
O(7^5)
sage: x.denominator()
Traceback (most recent call last):
...
ValueError: Cannot determine the denominator of an element indistinguishable from 0

lift_to_precision(absprec=None)

Return another element of the same parent with absolute precision at least absprec, congruent to this element modulo the precision of this element.

INPUT:

• absprec – an integer or None (default: None), the absolute precision of the result. If None, lifts to the maximum precision allowed.

Note

If setting absprec that high would violate the precision cap, raises a precision error. Note that the new digits will not necessarily be zero.

EXAMPLES:

sage: R = ZpCA(17)
sage: R(-1,2).lift_to_precision(10)
16 + 16*17 + O(17^10)
sage: R(1,15).lift_to_precision(10)
1 + O(17^15)
sage: R(1,15).lift_to_precision(30)
Traceback (most recent call last):
...
PrecisionError: Precision higher than allowed by the precision cap.
sage: R(-1,2).lift_to_precision().precision_absolute() == R.precision_cap()
True

sage: R = Zp(5); c = R(17,3); c.lift_to_precision(8)
2 + 3*5 + O(5^8)
sage: c.lift_to_precision().precision_relative() == R.precision_cap()
True

valuation()

Return the valuation of this element.

EXAMPLES:

sage: R = Zp(7)
sage: x = R(7); x
7 + O(7^21)
sage: x.valuation()
1

super_categories()

EXAMPLES:

sage: CompleteDiscreteValuationRings().super_categories()
[Category of discrete valuation rings]