#5159: [with new patch, needs review] Add functionality to Galois groups
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 Reporter:  davidloeffler  |       Owner:  davidloeffler               
     Type:  enhancement    |      Status:  assigned                    
 Priority:  major          |   Milestone:  sage-3.4.2                  
Component:  number theory  |    Keywords:  galois groups, number theory
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Comment(by davidloeffler):

 I've rebased it to a patch based on (3.4 + the patch for #5508).

 This version actually adds quite a bit that wasn't in the previous
 version: based on the debate on sage-nt, I've made it return the Galois
 group of the splitting field when the given field isn't Galois, and also
 added a method fixed_field for subgroups of Galois groups based on Pari's
 "galoisfixedfield".

 In an ideal world, when given a non-Galois field, it would return the
 Galois group of the Galois closure of the given field, but represented as
 permutations of the roots of the defining polynomial of the original
 field. I couldn't work out an easy way of doing this which wouldn't be
 horribly slow in general, so elements are represented as permutations of
 the Galois conjugates of some single element generating the Galois
 closure.

 I've also ReSTified class_group.py and number_field_ideal.py (the latter
 because I was editing it anyway, and the former because it was easy to
 do); and deprecated galois_group and is_galois for relative fields in
 favour of explicitly relative and absolute variants.

-- 
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/5159#comment:5>
Sage <http://sagemath.org/>
Sage - Open Source Mathematical Software: Building the Car Instead of 
Reinventing the Wheel

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