[HN Gopher] Does there exist a complete implementation of the Ri...
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       Does there exist a complete implementation of the Risch algorithm?
        
       Author : thechao
       Score  : 67 points
       Date   : 2023-08-14 17:43 UTC (5 hours ago)
        
 (HTM) web link (mathoverflow.net)
 (TXT) w3m dump (mathoverflow.net)
        
       | Havoc wrote:
       | No idea, but I am impressed by the clarity and preciseness of the
       | question
        
       | jjtheblunt wrote:
       | I'd check Mathematica or Macaulay2...but how would you verify an
       | implementation is complete?
        
         | jychang wrote:
         | It's written in the mathoverflow question, did you read it?
         | 
         | > I have access to Maple 2018, and it doesn't seem to have a
         | complete implementation either. A useful test case is the
         | following integral, taken from the (apparently unpublished)
         | paper Trager's algorithm for the integration of algebraic
         | functions revisited by Daniel Schultz: [?]29x2+18x-3x6+4x5+6x4-
         | 12x3+33x2-16x-----------------------------[?]dx Schultz
         | explicitly provides an elementary antiderivative in his paper,
         | but Maple 2018 returns the integral unevaluated.
        
           | cvoss wrote:
           | The question at hand is "how do you verify that an
           | implementation is complete?", not "what is one test case
           | whose failure would demonstrate that an implementation is
           | incomplete?"
        
           | jjtheblunt wrote:
           | That's not what i asked.
           | 
           | For example, you could have an implementation that handles
           | the example you cited, but fails at others you did not
           | mention. So would your comment claim "complete" for handling
           | what you mentioned, when it is not?
        
           | [deleted]
        
         | irrep wrote:
         | Mathematica does not have a complete implementation of the
         | Risch algorithm. It actually cannot do the integral in the
         | mathoverflow question.
         | 
         | Macaulay2 has a focus on commutative algebra and algebraic
         | geometry and doesn't have an implementation of the Risch
         | algorithm either.
        
       | 1letterunixname wrote:
       | I wonder how Giac measures up as it's reportedly more general
       | than HP48's Erable.
       | 
       | https://en.wikipedia.org/wiki/Xcas#Giac
       | 
       | PS: The HP 48 could also be used a very long distance remote to
       | turn on and off all of the TVs in a lecture hall simultaneously.
       | :)
        
       | irrep wrote:
       | Manuel Bronstein wrote a book [1] about symbolic integration, but
       | unfortunately it only covers the transcendental part. There is
       | also a shorter "tutorial" from some workshop [2].
       | 
       | [1] Manuel Bronstein: Symbolic Integration I,
       | https://doi.org/10.1007/b138171
       | 
       | [2] https://www-
       | sop.inria.fr/cafe/Manuel.Bronstein/publications/...
        
         | slavapestov wrote:
         | Sadly he passed away before completing Part 2.
         | https://lists.gnu.org/archive/html/axiom-developer/2005-06/m...
        
       | downvotetruth wrote:
       | https://news.ycombinator.com/item?id=589004
       | 
       | https://news.ycombinator.com/item?id=19291578
       | 
       | Not sure of a connection between the failure of the high school
       | axiom set / nonfiniteness of axioms and Rubi/rule based
       | integration feasiblility or validity of Schanuel's conjecture.
        
       | tehsauce wrote:
       | Does this count?
       | 
       | https://github.com/sympy/sympy/blob/master/sympy/integrals/r...
        
         | owalt wrote:
         | This does not - according to what I can see from the code and
         | comments - implement the case of algebraic extensions. As
         | someone only really familiar with the implementation of the
         | transcendental case[1], my understanding is that the algebraic
         | case is where the major difficulty lies.
         | 
         | [1]: Manuel Bronstein, Symbolic Integration I. Online:
         | https://archive.org/details/springer_10.1007-978-3-662-03386...
        
         | irrep wrote:
         | Unfortunately this is not complete, because it does not work
         | with integrals that require algebraic extensions (they are more
         | complicated than transcendental extensions).
        
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       (page generated 2023-08-14 23:00 UTC)