In that case, this might do it
sage: PermutationOptions(display='list')
sage: L1 = [5,3,8,6]
sage: L2 = copy(L1)
sage: L1.sort()
sage: L = [L2.index(x)+1 for x in L1]
sage: p = Permutation(L); p; p.to_cycles()
[2, 1, 4, 3]
[(1, 2), (3, 4)]
sage: p.signature()
1
sage: p.to_permutation_group_element().sign()
1
On Mon, Jun 30, 2008 at 9:12 PM, John H Palmieri <[EMAIL PROTECTED]> wrote:
>
>
>
> On Jun 30, 5:16 pm, "David Joyner" <[EMAIL PROTECTED]> wrote:
>> Do you mean the tuple is represented in the disjoint cycle notation and
>> is a cyclic permutation? In that case, you can use:
>>
>> sage: PermutationGroupElement('(3,6,4)').sign()
>> 1
>> sage: PermutationGroupElement('(5,3,6,4)').sign()
>> -1
>>
>
> No, by "one-line permutation notation", I mean that (3,6,4) means the
> permutation where 3 -> 3, 4 -> 6, and 6 -> 4, while (5,3,8,6) is the
> permutation of (3,5,8,6) in which 3 and 5 have been interchanged, as
> have 6 and 8.
>
>
>> On Mon, Jun 30, 2008 at 7:17 PM, John H Palmieri <[EMAIL PROTECTED]> wrote:
>>
>>
>>
>> > Suppose I have a tuple x of distinct non-negative integers. Is there
>> > a quick way to find the sign of this, as a permutation of Set(x)? (I
>> > want to view x as the one-line permutation notation form, so (3,6,4)
>> > will have sign -1, while (5,3,8,6) will have sign 1.)
>>
>> > The things I can find in combinat/... don't quite seem to do what I
>> > want. I can build something myself, but if there is a quick solution,
>> > I would prefer that.
> >
>
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