#19040: defuse bool(x!=0) performance bomb
-------------------------+-------------------------------------------------
Reporter: rws | Owner:
Type: | Status: new
enhancement | Milestone: sage-6.9
Priority: major | Resolution:
Component: | Merged in:
symbolics | Reviewers:
Keywords: | Work issues:
Authors: Ralf | Commit:
Stephan | 800ec56b0b930eb8a5b966c5871dc5e76724acb0
Report Upstream: N/A | Stopgaps:
Branch: |
u/rws/19040 |
Dependencies: |
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Description changed by rws:
Old description:
> Symbolics may be part of type-neutral computations, e.g. matrices, rings.
> Developers do not expect proof machinery to crank up when writing `if
> x!=0`, so `bool(x1!=x2)` should mean `not (x1-x2).is_trivial_zero()` for
> symbolic `x`. We should provide a different interface for cases requiring
> simplification/proof:
> * `bool(rel)` equivalent to `(not)(LHS-RHS).is_trivial_zero()` for ==,!=
> ; and an exception with maybe hint to the following for <,>,<=,>=
> * `satisfiable(rel)` returning
> `(Yes,example)/No/Undecidable/NotImplemented`
> * `truth(rel, (x,S1), (y,S1)...)` equivalent to `satisfiable(rel)` for
> all `x,y...` in `S1,S2,...`
> * `solve(rel)` in case of `satisfiable=Yes` returning the full solution
> set
> * `prove(rel)` showing more or less steps of simplification (which is
> out of reach for the moment)
>
> This ticket will implement the new behaviour of `bool(rel)` and put all
> other functionality of `ex.__nonzero__()` into `ex.satisfiable()`.
>
> See also #19162.
New description:
Symbolics may be part of type-neutral computations, e.g. matrices, rings.
Developers do not expect proof machinery to crank up when writing `if
x!=0`, so `bool(x1!=x2)` should mean `not (x1-x2).is_trivial_zero()` for
symbolic `x`. We should provide a different interface for cases requiring
simplification/proof:
* `bool(rel)` equivalent to `(not)(LHS-RHS).is_trivial_zero()` for ==,!=
; and an exception with maybe hint to the following for <,>,<=,>=
* `satisfiable(rel)` returning
`(Yes,example)/No/Undecidable/NotImplemented`
* `holds(rel, (x,S1), (y,S1)...)` equivalent to `satisfiable(rel)` for
all `x,y...` in `S1,S2,...`
* `solve(rel)` in case of `satisfiable=Yes` returning the full solution
set
* `prove(rel)` showing more or less steps of simplification (which is out
of reach for the moment)
This ticket will implement the new behaviour of `bool(rel)` and put all
other functionality of `ex.__nonzero__()` into `ex.satisfiable()`.
See also #19162.
--
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Ticket URL: <http://trac.sagemath.org/ticket/19040#comment:17>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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