#7145: Interval exchange transformations
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Reporter: vdelecroix | Owner: vdelecroix
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-4.3
Component: combinatorics | Keywords:
Work_issues: | Author: Vincent Delecroix
Upstream: N/A | Reviewer:
Merged: |
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Comment(by vdelecroix):
Replying to [comment:5 slabbe]:
> Vincent, I tried your code again with Thierry Monteil who knows better
this field and he liked all the functions you implemented.
>
> He suggested that you change Permutation* to `LabelledPermutation` or
`PermutationwithLabel`... up to you.
It won't be possible. I consider two kinds of permutations
* ReducedPermutation
* LabelledPermutation
A ReducedPermutation can be identified with a permutation of an ordered
alphabet.
A Labeledpermutation is a couple of bijection (p_t,p_b) : alphabet ->
[1,n]
> Also, I notice the following. I think it should be a method and not an
attribute :
>
> {{{
> sage: p = Permutation([4,3,2,1])
> sage: pp = PermutationIET(p)
> sage: pp.alphabet
> Ordered Alphabet [1, 2, 3, 4]
> }}}
The resason is because it's possible to change the alphabet
sage: p = PermutationIET('a b c','c b a')
sage: p
a b c
c b a
sage: p.alphabet = [1,2,3]
sage: p
1 2 3
3 2 1
sage: p.alphabet = 'cd'
...
ValueError: Your alphabet has not enough letters
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/7145#comment:6>
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