[GiNaC-list] How to express and simplify symbolic expressions in Ginac?

[Vladimir V. Kisil]

	Hello,

	Indeed, GiNaC does not provide a special class for boolean
  symbols. Probably, there is another C++ library, which can do
  this.

  Of course, you can partially model boolean values false/true by
  zero/non-zero and logical and/or with  ×/+. Furthermore, you may
  simplify expressions by substitution (pow(wild(0),wild(1)) == wild(0)).
  For boolean negation you may need a new function to be defined, say
  neg(x), with a further substitution
  ({wild(0)*neg(wild(0)) == 0, wild(0)+neg(wild(0)) == 1}), etc.  

  Best wishes,
  Vladimir
-- 
Vladimir V. Kisil                 http://www1.maths.leeds.ac.uk/~kisilv/
  Book:      Geometry of Mobius Maps       https://doi.org/10.1142/p835
  Soft:      Geometry of cycles         http://moebinv.sourceforge.net/
  Jupyter notebooks:        https://github.com/vvkisil?tab=repositories
>>>>> On Wed, 19 Apr 2023 17:51:46 -0700, "Anubhavnidhi Abhashkumar . via GiNaC-list" <ginac-list at ginac.de> said:

    AA> Hi,

    AA> I am pretty new to GiNac library in c++ and am struggling with
    AA> one particular topic. I have been using ginac-1.8.6

    AA> I want to represent and simplify symbolic expressions
    AA> (expressions with union, intersection, and not operator) with
    AA> GiNac. I have been trying the following example

    AA> #include <iostream>#include <ginac/ginac.h>using namespace
    AA> std;using namespace GiNaC; int main(){ symbol x("x"), y("y"),
    AA> z("z"); ex boolean_expr = (!x || y) && (x || z); cout <<
    AA> "Boolean expression: " << boolean_expr << endl;

    AA>     ex simplified_expr = normal(boolean_expr); cout <<
    AA> "Simplified expression: " << simplified_expr << endl;

    AA>     return 0; }

    AA> But I keep on getting errors related to ||, !, and &&
    AA> operators. For example,

    >> note: candidate: ‘operator!(bool)’ <built-in> note: no known
    >> conversion for argument 1 from ‘GiNaC::symbol’ to `bool’ error:
    >> no match for ‘operator!’ (operand type is `GiNaC::symbol’)


    AA> I also tried replacing ||, !, and && to or, not, and,
    AA> respectively but get similar errors

    >> error: no match for ‘operator!’ (operand type is ‘GiNaC::symbol’)
    AA>           ex boolean_expr = not(x) or y and (x or not(z));


    AA> So my question is how can I represent and, or, not. I am using
    AA> Ginac 1.8.6 from here <https://www.ginac.de/Download.html>. I
    AA> also checked the manual here <https://www.ginac.de/tutorial.pdf>
    AA> but did not find an answer.

    AA> Thanks, Archie http://anubhavnidhi.github.io/