trac #15471: getting rid of a pointless product with an identity permutation
trac #15471: reviewer's patch
Minor tweak to tableau.py
Trac 15052: Fixes infinite loop bug
added max_entry option to SemistandardSkewTableaux
allowing max_entry for tableaux of given size as well, and documenting the erratic behavior of this class (hopefully subject to later refactoring)
SemistandardSkewTableaux(max_entry) now also well-defined
documented a pecularity of skew partition/tableau iterators
sphinx oops fixed
Fixed SetSystem._isomorphism(S,T) where S is an empty isopmorphism.
trac #15769: Rebase on 6.2.beta0
trac #15769: replace "if len(L) > 0:" with "if L:"
PARI: fix pow, mod and shift operators
Trac #15052: plot_field crashes if if self.options() is called for an object with an unknown option

Consider the following example:

{{{
sage: x,y=var('x,y')
sage: P=plot_vector_field((sin(x), cos(y)), (x,-3,3), (y,-3,3),
wrong_option='nonsense')
sage: P[0].options()['plot_points']
}}}

One would expect that this returns the value of plot_points together
with a warning that a unknown option is set. Instead it enters an
infinite loop and crashes

----

apply trac_15052_fixes_infinite_loop.patch​ to devel/sage

URL: http://trac.sagemath.org/15052
Reported by: twch
Ticket author(s): Tobias Weich
Reviewer(s): Punarbasu Purkayastha
Trac #15471: sage/graphs/generators/intersection.py multiplies a permutation by id

and no, it's not even a poor man's coercion, because they have the same
size already. My bet is someone was confused. The attached patch (split
out of #15174) removes this exercise in futility.

URL: http://trac.sagemath.org/15471
Reported by: darij
Ticket author(s): Darij Grinberg
Reviewer(s): Nathann Cohen
Trac #15785: PARI: allow non-gen as "self" argument for __pow__

{{{
sage: int(2)^pari(2.5)
------------------------------------------------------------------------
---
TypeError                                 Traceback (most recent call
last)
<ipython-input-1-bbaff70c173b> in <module>()
----> 1 int(Integer(2))**pari(RealNumber('2.5'))

TypeError: Argument 'self' has incorrect type (expected
sage.libs.pari.gen.gen, got int)
}}}

We should probably also implement modular `__pow__` and fix a few other
operators with the same problem.

URL: http://trac.sagemath.org/15785
Reported by: jdemeyer
Ticket author(s): Jeroen Demeyer
Reviewer(s): David Roe
Trac #15769: SetSystem._isomorphism fails on an empty Setsystem

The following produces an error:
{{{
from sage.matroids.set_system import SetSystem
S=SetSystem([],[])
S._isomorphism(S)
}}}
_equivalence() has a similar problem.

URL: http://trac.sagemath.org/15769
Reported by: Rudi
Ticket author(s): Rudi Pendavingh
Reviewer(s): Nathann Cohen
Trac #15752: Change in iterator for SemistandardSkewTableaux_shape

The iterator for
{{{
class SemistandardSkewTableaux_shape
}}}
runs over all weights in
{{{
IntegerVectors(self.p.size(), self.p.size())
}}}
which seems rather arbitrary. To conform with the iterator in the
analogous class
{{{
class SemistandardTableaux_shape
}}}
we will allow for an additional entry `max_entry`.

URL: http://trac.sagemath.org/15752
Reported by: aschilling
Ticket author(s): Anne Schilling, Darij Grinberg
Reviewer(s): Darij Grinberg, Anne Schilling
Trac #15655: Tweak to improve speed of generating standard tableaux

In the iterator for generating standard tableaux the lexicographically
last tableau is re-recomputed every time the iterator yields. Taking
this out leads to a small speed improvements when generating moderately
large sets of tableaux:

The following table shows the timings for
{{{
    sage: for n in range(5,15):
    ....:     timeit("StandardTableaux(n)[:];",number=6)
}}}
before and after the patch:

||= **n**  ||=    **Before**    =||= **After** =||
|| 5||    6.2ms||  5.4ms||
|| 6||   14.0ms|| 12.4ms||
|| 7||   43.3ms|| 40.5ms||
|| 8||    151ms||  140ms||
|| 9||    558ms||  509ms||
||10||    2.14s||  1.97s||
||11||    8.56s||  7.82s||
||12||    35.4s|| 34.55s||
||13||  161.57s||145.11s||
||14||  711.13s||633.93s||

These timings were done on my laptop, a macbook pro running sage 6.0.
(Actually, the last two sets were done with just one timing:)

URL: http://trac.sagemath.org/15655
Reported by: andrew.mathas
Ticket author(s): Andrew Mathas
Reviewer(s): Travis Scrimshaw