#16676: Cardinality of infinite sets loops forever
-------------------------------------+-------------------------------------
Reporter: defeo | Owner:
Type: defect | Status: positive_review
Priority: major | Milestone: sage-
Component: combinatorics | duplicate/invalid/wontfix
Keywords: sets | Resolution:
infinite_loop | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Changes (by ncohen):
* status: needs_review => positive_review
Comment:
> {{{
> sage: Set(ZZ).difference(Set()).cardinality()
> +Infinity
> sage: Set(QQ).difference(Set(ZZ)).cardinality()
> NotImplementedError: computation of cardinality of Set-theoretic
> difference of Set of elements of Rational Field and Set of elements
> of Integer Ring not yet implemented
> }}}
Perhaps we should start adding parentheses in those error messages.
Something like
{{{
computation of cardinality of (Set-theoretic
difference of Set of elements of Rational Field) and (Set of elements
of Integer Ring) not yet implemented.
}}}
But then we would eventually end up with the more lisp-looking message
{{{
computation of cardinality of (Set-theoretic
difference of Set of elements of (Rational Field)) and (Set of elements
of (Integer Ring)) not yet implemented.
}}}
Sigh... `:-P`
Nathann
--
Ticket URL: <http://trac.sagemath.org/ticket/16676#comment:11>
Sage <http://www.sagemath.org>
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