#19498: Random failure in Integers(15).fraction_field()
-------------------------------------+-------------------------------------
Reporter: jdemeyer | Owner:
Type: defect | Status: positive_review
Priority: blocker | Milestone: sage-6.10
Component: categories | Resolution:
Keywords: random_fail | Merged in:
Authors: Jeroen Demeyer | Reviewers: Travis Scrimshaw
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/jdemeyer/random_failure_in_integers_15__fraction_field__|
bb091596d543140f5077e05698b2f18e4711bddd
Dependencies: | Stopgaps:
-------------------------------------+-------------------------------------
Changes (by tscrim):
* status: needs_review => positive_review
* reviewer: => Travis Scrimshaw
Comment:
Your commit looks good to me and fixes the doctest at hand.
However the actual issue has something very subtle going on. Something
strange is happening here:
{{{
sage: x = 20
sage: Integers(x).category()
Join of Category of finite commutative rings and Category of subquotients
of monoids and Category of quotients of semigroups and Category of finite
enumerated sets
sage: Integers(x, is_field=True).category()
Join of Category of finite fields and Category of subquotients of monoids
and Category of quotients of semigroups
sage: gc.collect()
186
sage: gc.collect()
0
sage: Integers(x).category()
Join of Category of finite commutative rings and Category of subquotients
of monoids and Category of quotients of semigroups and Category of finite
enumerated sets
}}}
However, then doing the commands in comment:2 nails any of these in
memory. We also have this:
{{{
sage: Integers(int(20), is_field=True).category()
Join of Category of finite fields and Category of subquotients of monoids
and Category of quotients of semigroups
sage: Integers(int(20)).category()
Join of Category of finite fields and Category of subquotients of monoids
and Category of quotients of semigroups
sage: gc.collect()
136
sage: gc.collect()
0
sage: Integers(int(20)).category()
Join of Category of finite commutative rings and Category of subquotients
of monoids and Category of quotients of semigroups and Category of finite
enumerated sets
}}}
Even more strangeness as this works:
{{{
sage: Integers(Integer(20)).category()
Join of Category of finite commutative rings and Category of subquotients
of monoids and Category of quotients of semigroups and Category of finite
enumerated sets
sage: Integers(Integer(20), is_field=True).category()
Join of Category of finite fields and Category of subquotients of monoids
and Category of quotients of semigroups
sage: gc.collect()
251
sage: gc.collect()
0
sage: Integers(Integers(20)).category()
---------------------------------------------------------------------------
TypeError Traceback (most recent call
last)
...
TypeError: unable to coerce <class
'sage.rings.finite_rings.integer_mod_ring.IntegerModRing_generic_with_category'>
to an integer
sage: Integers(Integer(20)).category()
Join of Category of finite commutative rings and Category of subquotients
of monoids and Category of quotients of semigroups and Category of finite
enumerated sets
}}}
versus this which doesn't:
{{{
sage: Integers(Integer(20), is_field=True).category()
Join of Category of finite fields and Category of subquotients of monoids
and Category of quotients of semigroups
sage: gc.collect()
64
sage: gc.collect()
0
sage: Integers(Integer(20)).category()
Join of Category of finite fields and Category of subquotients of monoids
and Category of quotients of semigroups
sage: Integers(Integers(20)).category()
---------------------------------------------------------------------------
TypeError Traceback (most recent call
last)
...
TypeError: unable to coerce <class
'sage.rings.finite_rings.integer_mod_ring.IntegerModRing_generic_with_category'>
to an integer
sage: Integers(Integer(20)).category()
Join of Category of finite fields and Category of subquotients of monoids
and Category of quotients of semigroups
}}}
--
Ticket URL: <http://trac.sagemath.org/ticket/19498#comment:6>
Sage <http://www.sagemath.org>
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