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Bug #1237

ker: for PolyAlgHom from QQ[x,y,z] to QQ(t)

Added by John Abbott over 5 years ago. Updated almost 3 years ago.

Status:
New
Priority:
Normal
Assignee:
-
Category:
enhancing/improving
Target version:
CoCoA-5.4.2
Start date:
15 Jan 2019
Due date:
% Done:

0%

Estimated time:

Description

Should we make ker work also for cases like the following?

>>> QQt ::= QQ[t];
>>> KQQt := NewFractionField(QQt);
>>> t := indet(QQt,1);
>>> embed := CanonicalHom(QQt,KQQt);
>>> t := embed(t)
>>> QQxy ::= QQ[x,y];
>>> phi := PolyAlgebraHom(QQxy,KQQt, [ 3*t/(t^3+1), 3*t^2/(t^3+1) ]);
>>> ker(phi);
--> ERROR: RINGHOM must be between poly rings or their quotients: 
--> [CoCoALib] ker
--> ker(phi);
--> ^^^^^^^^

History

#1 Updated by John Abbott almost 3 years ago

  • Category set to enhancing/improving
  • Target version set to CoCoA-5.4.2

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