trac #15345 first step: coercion of Laurent polynomials into fractions
trac #15345 corrected code
trac #15345 better coercion
trac #15345 documentation added
Use fraction field of polynomial ring for fraction field of Laurent polynomial ring
trac #15345 corrected doctests in hall algebra
Fixed documentation for hall_algebra.py.
Renamed to_fraction to _fraction_pair.
Trac #11005: Update Simon's GP scripts

[See #15608 for a list of open simon_two_descent tickets]

Denis Simon has new versions of his scripts (see
[http://www.math.unicaen.fr/~simon/]), these should be updated (see
`src/ext/pari/simon`).

URL: http://trac.sagemath.org/11005
Reported by: cremona
Ticket author(s): Peter Bruin
Reviewer(s): Jeroen Demeyer
Trac #15668: implement the fixed complex of automorphisms of simplicial complexes

This is a useful tool to have, I think.

URL: http://trac.sagemath.org/15668
Reported by: chapoton
Ticket author(s): Frédéric Chapoton
Reviewer(s): Travis Scrimshaw
Trac #15762: Make R and its extensions build on ARM

Make R and its extensions build on ARM with broken regexp in libc.

URL: http://trac.sagemath.org/15762
Reported by: dimpase
Ticket author(s): Dmitrii Pasechnik
Reviewer(s): Jean-Pierre Flori
Trac #15787: Files needed in SAGE_ATLAS_LIB

Following the conversation on sage-release [1]. It looks like the files
libptcblas and libptf77blas are not actually required by Atlas. And
debian does not contain them anyway.

Nathann

[1] https://groups.google.com/d/msg/sage-release/oxGODejce_0/yuJp4ZM-
9ksJ

URL: http://trac.sagemath.org/15787
Reported by: ncohen
Ticket author(s): Nathann Cohen
Reviewer(s): Ralf Stephan
Trac #15482: Say very loud that LP variables are non-negative by default

As the title says. It has been reported once again. We make this
assumption because ALL lp solvers that we use make the same, but it does
not mean everybody knows it `T_T`

Nathann

URL: http://trac.sagemath.org/15482
Reported by: ncohen
Ticket author(s): Nathann Cohen
Reviewer(s): Punarbasu Purkayastha, Karl-Dieter Crisman, Thierry Monteil
Trac #15345: Laurent polynomial rings don't preserve coercion

{{{
sage: R = LaurentPolynomialRing(ZZ, 'x')
sage: T = LaurentPolynomialRing(QQ, 'x')
sage: R.gen() + T.gen()
------------------------------------------------------------------------
---
TypeError                                 Traceback (most recent call
last)
<ipython-input-3-dac3b0b430b6> in <module>()
----> 1 R.gen() + T.gen()

/home/darij/sage-5.13.beta0/local/lib/python2.7/site-
packages/sage/structure/element.so in
sage.structure.element.RingElement.__add__
(sage/structure/element.c:13884)()

/home/darij/sage-5.13.beta0/local/lib/python2.7/site-
packages/sage/structure/coerce.so in
sage.structure.coerce.CoercionModel_cache_maps.bin_op
(sage/structure/coerce.c:8169)()

TypeError: unsupported operand parent(s) for '+': 'Univariate Laurent
Polynomial Ring in x over Integer Ring' and 'Univariate Laurent
Polynomial Ring in x over Rational Field'
}}}
Compare with the more complicated:
{{{
sage: R = PolynomialRing(ZZ, 'x').fraction_field()
sage: T = PolynomialRing(QQ, 'x').fraction_field()
sage: R.gen() + T.gen()
2*x
}}}

URL: http://trac.sagemath.org/15345
Reported by: darij
Ticket author(s): Frédéric Chapoton, David Roe
Reviewer(s): Travis Scrimshaw