prime must be a prime in the integers but 2 is not

asked 2025-12-07 11:27:33 +0100

juan
3 ●1

I put

v = QQ.valuation(2)

and get the error prime must be a prime in the integers but 2 is not

Comments

It works fine at sagecell. What is your Sage version and what error do you see?

Max Alekseyev ( 2025-12-08 12:06:04 +0100 )edit

It is Sage 10.6 the error is after import something:

from sympy import * 123.valuation(3)

AttributeError Traceback (most recent call last) Cell In[2], line 2 1 from sympy import * ----> 2 Integer(123).valuation(Integer(3))

AttributeError: 'Integer' object has no attribute 'valuation'

Yesterday I was trying many things and end with the absurd error " prime must be a prime in the integers but 2 is not" Today I can not reproduce this error, but first it is the one above.

juan ( 2025-12-08 20:44:17 +0100 )edit

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answered 2025-12-08 20:59:28 +0100

Max Alekseyev

7303 ●10 ●63 ●178

updated 2025-12-08 21:33:07 +0100

The problem is caused by from sympy import * overwriting the definition of Sage's Integer class:

print(Integer)
from sympy import * 
print(Integer)

prints:

<class 'sage.rings.integer.Integer'>
<class 'sympy.core.numbers.Integer'>

Possible solutions:

import only really needed stuff from sympy, not *
or re-import Integer from Sage:

from sympy import *

from sage.rings.integer import Integer
or explicitly specify the type of 123 - like:

ZZ(123).valuation(3)

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But still I have problems: I have definitions in a file,I make it minimal with: from sympy import divisors from mpmath import log from sage.rings.integer import Integer

def decompose(n): d=divisors(n)[1] d=ZZ(d) a=d.valuation(2) return a

then with from MinimalExample import * decompose(12345) get an error: name 'ZZ' is not defined

if I eliminate d=ZZ(D) the error is: AttributeError: 'int' object has no attribute 'valuation'

juan ( 2025-12-09 10:45:18 +0100 )edit

Are you running your example from Sage? Otherwise you also need from sage.all import *

Max Alekseyev ( 2025-12-09 13:04:54 +0100 )edit

Thank you!!! now it runs correctly.

juan ( 2025-12-09 13:15:55 +0100 )edit

Btw, divisors are present in Sage as well, you don't need sympy for that.

Max Alekseyev ( 2025-12-09 13:29:05 +0100 )edit

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