Trac #14823: Categories of (C)DVR and (C)DVF

Here is a small patch defining categories of (complete) discrete
valuation rings and (complete) discrete valuation fields.

URL: http://trac.sagemath.org/14823
Reported by: caruso
Ticket author(s): Xavier Caruso
Reviewer(s): David Roe
Trac #15576: Semimonomial transformation groups code is sensitive to Permutations global options

As detailed in #14885, it is not healthy for code to rely on the
`__mul__` operation on permutations, since this operation depends on the
`Permutations().global_options()['mul']` variable which can change at
runtime. It is better to use the `left_action_product` and
`right_action_product` methods introduced in #15174 (formerly known as
`_left_to_right_multiply_on_left` and
`_left_to_right_multiply_on_right`).

My tests show some dependence on the `__mul__` method in `sage/groups/se
mimonomial_transformations/semimonomial_transformation.pyx` and `sage/gr
oups/semimonomial_transformations/semimonomial_transformation_group.py`,
although it might be that only one of these files depends on it and the
other depends on the first file. Unfortunately I don't have time to
study this in detail, as I'd first have to read up on the definitions.

URL: http://trac.sagemath.org/15576
Reported by: darij
Ticket author(s): Thomas Feulner
Reviewer(s): Darij Grinberg
Trac #15613: Implementation for check of perfectness for CrystalOfProjectedLevelZeroLSPaths

This ticket implements a check for perfectness of
CrystalOfProjectedLevelZeroLSPaths.

URL: http://trac.sagemath.org/15613
Reported by: aschilling
Ticket author(s): Anne Schilling
Reviewer(s): Travis Scrimshaw