Le mardi 18 novembre 2014 17:10:42 UTC+1, Chris Seberino a écrit :
>
> Emmanuel
>
> Any way to make Sage act like it can't find the solution (emit question
> back to user) INSTEAD of emitting the empty set?
>
> "I can't find the solution" and "There is no solution" are NOT the same
> thing?
>
Indeed. But proving that "There is no solution" might inded invorve some
serious work. Consider (pseudocode) :
var("a,b,c,n")
assume(a,"integer",b,"integer",c,"integer",n,"integer",a>0,b>0,c>0,n>2)
solve(a^n+b^n==c^n,[a,b,c,n])
which has, indeed no solution. Proving this has been found a bit involved...
So you can assume that an empty list means only that sage's algorithms find
no solution.
Your point is that, in your example, sage returns (incorrectly) an empty
list.In other cases, it returns the original equation.
Indeed. So what ?
I have not (yet) found a specification for those two cases, but I think it
depends on which algorithm has been used. (Maxima may return the empty list
in cases solve'() does not succeds).
Beware : in other cases, sage might return an implicit solution, given as
an equation.
> cs
>>>
>>
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