#20920: Changes to Unknown class
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Reporter: eviatarbach | Type: PLEASE CHANGE
Status: new | Priority: major
Milestone: sage-7.3 | Component: misc
Keywords: days78 | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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The `Unknown` class currently evaluates to `False` when converted to a
boolean. This also leads to wrong results when using the logical
operators, as explained in `unknown.py`.
This ticket makes evaluating the truth value of `Unknown` with
`__nonzero__` an error, meaning that logical operations must be done only
with the bitwise operators. It also adapts the `UnknownClass` to add
support for an `Undecidable` object, which is similar to `Unknown` but
intended specifically for cases when an answer is known to be formally
undecidable. This is useful for #17700.
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Ticket URL: <https://trac.sagemath.org/ticket/20920>
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