#12650: Perform safe simplifications in Expression.simplify()
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Reporter: mjo | Owner: mjo
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-5.0
Component: symbolics | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers: David Roe
Authors: Michael Orlitzky | Merged in:
Dependencies: | Stopgaps:
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Comment (by mjo):
Replying to [comment:6 kcrisman]:
> I don't think this is the right fix.
> * Breaks behavior for no reason
> * Breaks with our recent trajectory of ''adding'' access to Maxima
stuff and granularity
> * Makes users have to do much more than needed for the super-basic
simplifications that Maxima did
> Now, maybe we should do more in `simplify`. But it seems sort of
redundant to ''remove'' `radcan` from `simplify_full` and then ''add''
everything else here anyway.
>
> I think that it might make sense to look over the Maxima documentation
and ''code'' very carefully and determine if something like the factorial
simplification truly is the same in all cases, like it would be with
`expand`. Otherwise it seems unwise to make this change.
>
> I'm especially mystified as to what the difference between `simplify`
and `simplify_full` should be under this regime.
I brought this up in my initial message to sage-devel, but didn't get any
comments. I agree it's not perfect, but,
* Most of the simplifications we do are pretty basic anyway. I think it
makes sense to have `simplify()` actually attempt ''something''. If we
ever discover that the simplifications in `simplify()` are misbehaving,
they can just be removed.
* `full_simplify()` used to make two calls to `simplify_rational()` In
#12737 I've got it making two calls to `simplify()` so it isn't
''completely'' redundant even with unsafe=False.
* New simplifications can be added to `full_simplify()`, for example
#11785. And maybe we could allow to take a complexity function as an
argument ala Mathematica.
I am open to other ideas, though. I personally would be satisfied with
`full_simplify()` if it were safe to call and I didn't have to define my
own `safe_simplify()`.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12650#comment:8>
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