#15157: Symmetric functions: degree_negation tacitly expects the input to be in
the
same basis
-------------------------+-------------------------------------------------
Reporter: darij | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-5.12
Component: | Keywords: symmetric function, combinat,
combinatorics | Sym, kronecker product
Merged in: | Authors: Darij Grinberg
Reviewers: | Report Upstream: N/A
Work issues: | Branch:
Commit: | Dependencies:
Stopgaps: |
-------------------------+-------------------------------------------------
The {{{degree_negation}}} method as I implemented it in #14775 would give
a wrong result when given a symmetric function in a different basis:
{{{
sage: Sym = SymmetricFunctions(QQ)
sage: Sym.inject_shorthands()
/home/darij/sage-5.11.beta3/local/lib/python2.7/site-
packages/sage/combinat/sf/sf.py:1197: RuntimeWarning: redefining global
value `e`
inject_variable(shorthand, getattr(self, shorthand)())
sage: h.antipode(e[3]) # WRONG
-h[1, 1, 1] + 2*h[2, 1] - h[3]
sage: h.antipode(h(e[3])) # correct
-h[3]
sage: h.degree_negation(e[3]) # WRONG
-h[3]
sage: h.degree_negation(h(e[3])) # correct
-h[1, 1, 1] + 2*h[2, 1] - h[3]
}}}
The attached patch fixes this (at no visible speed cost, I believe) and
also improves some documentation (I replaced "automorphism" by
"endomorphism" because those maps weren't always invertible).
--
Ticket URL: <http://trac.sagemath.org/ticket/15157>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/sage-trac.
For more options, visit https://groups.google.com/groups/opt_out.
