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## [Axiom-developer] [#191 exquo and therefore gcd cannot handle UP(x, EXPR

**From**: |
wyscc |

**Subject**: |
[Axiom-developer] [#191 exquo and therefore gcd cannot handle UP(x, EXPR INT)] plausible explanation |

**Date**: |
Mon, 11 Jul 2005 18:18:26 -0500 |

Changes
http://page.axiom-developer.org/zope/mathaction/191ExquoAndThereforeGcdCannotHandleUPXEXPRINT/diff
--
The problem is
\begin{axiom}
r := simplify (x-2^a)*(x+2^a)
gcd(p,r)
\end{axiom}
ends up in EXPR INT, not 'UP(x,EXPR INT)' which is entirely reasonable. But
then the 'x' in 'r' is no longer the same 'x' in p and hence the 'gcd(p,r)' is
1.
I don't think anything should be fixed. Users are responsible when they mix
variables in nested polynomial domains. Check out the code for
triangularSystems where careful pushing and pulling of these variables are done.
--
forwarded from http://page.axiom-developer.org/zope/mathaction/address@hidden

**[Axiom-developer] [#191 exquo and therefore gcd cannot handle UP(x, EXPR INT)] plausible explanation**,
*wyscc* **<=**