Composition of morphisms

[sagetrac-tfeulner]

The following code leads to a TypeError:

sage: F.<a> = GF(4)
sage: f = F.Hom(F).identity()
sage: g = F.hom([a])
sage: h = (g*f)
sage: f*h
...
TypeError: right (=Composite map:
  From: Finite Field in a of size 2^2
  To:   Finite Field in a of size 2^2
  Defn:   Identity endomorphism of Finite Field in a of size 2^2
        then
          Ring endomorphism of Finite Field in a of size 2^2
          Defn: a |--> a) must be a morphism to multiply it by Identity endomorphism of Finite Field in a of size 2^2

The problem is solved by relaxing the type checking in the multiplication procedure to accept Maps and not only Morphisms

CC: @simon-king-jena

Component: categories

Keywords: composition, morphisms, sd48

Author: Thomas Feulner

Reviewer: Volker Braun

Merged: sage-5.11.beta3

Issue created by migration from https://trac.sagemath.org/ticket/14537

[sagetrac-tfeulner]

Attachment: trac_14537_identity_morphism.patch.gz

[vbraun]

comment:2

Looks good to me

[vbraun]

Reviewer: Volker Braun

[vbraun]

Author: Thomas Feulner

[vbraun]

Changed keywords from composition, morphisms to composition, morphisms, sd48

[jdemeyer]

Merged: sage-5.11.beta3