Hellooooooooo everybody !
This afternoon I read the "Category Primer" [1] and I reviewed #15588.
Which means I know everything there is to know about categories.
If I understood well what Travis taught me in #15588, calling .category()
has no reason to give you the "Smallest category containing your set". It
will give you the "Smallest category computed so far".
Which can be different.
sage: F23 = IntegerModRing(23)
sage: F23.category().is_subcategory(Fields())
True
sage: F23 in Fields()
True
sage: F23.category().is_subcategory(Fields())
True
For this reason, I do not understand the code of
FiniteEnumeratedSets().__contains__ :
try:
c = x.category()
except AttributeError:
return False
return c.is_subcategory(self)
To me, this is wrong, as a set whose category does *not* specify anything
on the cardinality will be detected as non-Finite, without any actual
attempt at determining its cardinality.
Thanks for your help :-P
Nathann
[1]
http://www.sagemath.org/doc/reference/categories/sage/categories/primer.html
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