There is an explanation and a "solution" on the ticket.
Best
Vincent
Le 03/02/2022 à 23:48, Akos M a écrit :
Replacing 0 with self.zero() works perfectly, thank you!
Best,
Akos
On Thursday, February 3, 2022 at 11:34:43 PM UTC+1 Akos M wrote:
Thanks for the feedback.
Indeed, defined as such, C is a broken object - this was just the smallest
example where I could reproduce the error.
I was hoping that it should be possible to access the module elements
without referring to 1, or multiplication.
I would like to define multiplication later in the definition of some
algebraic structure, but still inherit the methods from the category.
(Similarly to
https://doc.sagemath.org/html/en/thematic_tutorials/coercion_and_categories.html
)
In particular, the error originally appeared in the form of
"if x == 0:"
where x is an element of the module, as should be 0 (now coerced..).
Best,
Akos
On Thursday, February 3, 2022 at 10:10:29 PM UTC+1 vdelecroix wrote:
Now I am thinking about it, I am not sure it is a bug. You did
not defined any algebra structure (neither the unit nor the
product on the basis). C is definitely a broken object.
However, it would make sense for C(0) not to call C(1).
Vincent
Le 03/02/2022 à 21:49, Akos M a écrit :
Thanks, I created - my first - ticket.
https://trac.sagemath.org/ticket/33285#ticket
Once the ticket is (eventually) resolved, how do I update sage to
involve
the resolution?
Thanks,
Akos
On Thursday, February 3, 2022 at 1:39:10 PM UTC+1 vdelecroix wrote:
It is definitely a bug. Do you know how to open
a ticket on the trac server ?
The infinite loop comes from C.one() calling C(1)
calling C.one()... When you specify a category
the inheritance is different and this explains
the difference of behaviour.
Best
Vincent
Le 03/02/2022 à 11:29, Akos M a écrit :
Hi,
The snippet
D = CombinatorialFreeModule(ZZ, [1,2]) D(0)
works fine, however
C = CombinatorialFreeModule(ZZ, [1,2],
category=AlgebrasWithBasis(ZZ))
C(0)
gets into an infinite loop:
File
"/opt/sagemath-9.0/local/lib/python3.7/site-packages/sage/categories/magmas.py",
line 488, in one return self(1) File "sage/structure/parent.pyx",
line
900,
in sage.structure.parent.Parent.__call__
(build/cythonized/sage/structure/parent.c:9218) return mor._call_(x)
File
"sage/categories/map.pyx", line 1694, in
sage.categories.map.FormalCompositeMap._call_
(build/cythonized/sage/categories/map.c:11607) x = f._call_(x) File
"sage/categories/morphism.pyx", line 549, in
sage.categories.morphism.SetMorphism._call_
(build/cythonized/sage/categories/morphism.c:8489) cpdef Element
_call_(self, x): File "sage/categories/morphism.pyx", line 568, in
sage.categories.morphism.SetMorphism._call_
(build/cythonized/sage/categories/morphism.c:8439) return
self._function(x)
File
"/opt/sagemath-9.0/local/lib/python3.7/site-packages/sage/categories/unital_algebras.py",
line 70, in from_base_ring return self.one()._lmul_(r) File
"sage/misc/cachefunc.pyx", line 2310, in
sage.misc.cachefunc.CachedMethodCallerNoArgs.__call__
(build/cythonized/sage/misc/cachefunc.c:12712) self.cache =
f(self._instance)
Why is this? Is this expected behaviour?
(Also asked on:
https://ask.sagemath.org/question/60903/possible-bug-specifying-category-messes-up-coercion/
)
Thanks,
Akos
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