Hi there,
I'm new to sage-devel. So I apologize in advance if I say things that make
no sense.
The order of the product of two permutations in sage struck me as well, as
many others, no doubt. As has been said, it does not really matter which
order has been chosen, as soon as the other order
Hi everyone,
Two updates on the topic of the multiplication order for permutations:
1) In trac #15174, I have implemented global-option-independent
multiplication methods for elements of symmetric group algebras. (Such
methods already existed for permutations -- I have now exposed them and
add
On Tue, Jul 16, 2013 at 2:07 PM, Simon King wrote:
> Hi David,
>
> On 2013-07-16, David Kohel wrote:
> > Defining the (left or right) action by * would probably be a
> > nightmare with the coercion model, since it is handled as
> > a symmetric operator.
>
> Is this really so?
>
> There is stuff
Hi David,
On 2013-07-16, David Kohel wrote:
> Defining the (left or right) action by * would probably be a
> nightmare with the coercion model, since it is handled as
> a symmetric operator.
Is this really so?
There is stuff in sage.structure.coerce, for example methods
R.get_action(S,opera
Hi,
I also strongly support both left and right actions, with the syntax
Left action:
s1(s2(x)) == (s1*s2)(x)
Right action:
(x^s1)^s2 == x^(s1*s2)
Currently the left (functional) notation is implemented in Sage with
the right order of application: s1(s2(x)) == (s2*s1)(x) is True.
This need
2013/7/15 Peter Bruin :
> Hi Marco and all,
>
>> I had Darij's problem as well, and many others probably did as well.
>> In a right action, I would prefer p(1) to give a warning. In a right
>> action, I would want some notation where p is on the right, preferably
>> 1^p (1 hat p).
>
>
> That would
On Mon, Jul 15, 2013 at 10:34 AM, Peter Bruin wrote:
> Hi Marco and all,
>
>> I had Darij's problem as well, and many others probably did as well.
>> In a right action, I would prefer p(1) to give a warning. In a right
>> action, I would want some notation where p is on the right, preferably
>> 1^
Hi Marco and all,
I had Darij's problem as well, and many others probably did as well.
> In a right action, I would prefer p(1) to give a warning. In a right
> action, I would want some notation where p is on the right, preferably
> 1^p (1 hat p).
>
That would make sense (except that I don't
2013/7/13 Volker Braun :
> But the question is, how is this right action that you speak of implemented
> in Sage?
+1 to this comment of Volker. And the notation should be "^" (hat)
I had Darij's problem as well, and many others probably did as well.
In a right action, I would prefer p(1) to give
Hi Darij,
On Sat, Jul 13, 2013 at 08:39:02PM +0200, Darij Grinberg wrote:
> One way to do it, of course, is by making the symmetric group algebra
> an AlgebraWithRealizations (like most combinatorial Hopf algebras),
> and implement the two different conventions as two different
> realizati
On Sunday, July 14, 2013 4:49:36 AM UTC-4, vdelecroix wrote:
> As Volker Braun mentioned, the main problem is that it is possible to
> write p(i) in Sage! I suggest that we remove the __call__ attribute of
> permutations (it does not exists in GAP but I do not know for other
> softwares). If we
Hi all,
On Sun, Jul 14, 2013 at 5:54 AM, Travis Scrimshaw wrote:
> Hey everyone who's following #14772,
>I don't want to change the patch, which has the multiplication in a
> GlobalOptions class, since it's just lifts the previous options up (a
> standard dict). Thus any change should depend
Here is a Sage argument in favor of right action: vectors are row vectors
in Sage (on which matrices act on right). There has been a choice to
silently ignore transposition and we can write vA or Av in Sage... but
still the natural way to do it is through right action (if we do it the
other way
On 2013-07-13, Darij Grinberg wrote:
> Hi Dima,
>
> On Sat, Jul 13, 2013 at 1:26 PM, Dima Pasechnik wrote:
>> IMHO it's a not as obsolete convention as you seem to imply; isn't e.g. Magma
>> using the same convention as GAP?
>> Not mentioning a lot of group theory literature...
>
> I don't know a
On Saturday, July 13, 2013 2:22:41 AM UTC-7, Darij Grinberg wrote:
> But if Judson's book uses right-to-left and Sage uses left-to-right,
> shouldn't your materials actually become easier to use once the dust has
> settled?
>
Yes, of course. It is me who will have trouble adjusting to the new
Hey everyone who's following #14772,
I don't want to change the patch, which has the multiplication in a
GlobalOptions class, since it's just lifts the previous options up (a
standard dict). Thus any change should depend on #14772 IMO. I'm not
attached to having multiplication be a global opt
Hi Nicolas, and hi all,
> - +1 on a parent option:
>
> sage: PermutationGroup(..., action='left')
>
> Note that this is consistent with what we do for finite set maps:
>
> sage: M = FiniteSetMaps([1, 2, 3], action = 'right')
>
> Maybe PermutationGroupElement will need to take a
On Sat, Jul 13, 2013 at 5:50 AM, Nicolas M. Thiery
wrote:
> Hi all,
>
> Thanks Darij for bringing up the issue, and everyone for your
> feedback! Here is my (strong for once) opinion on this issue.
+1 to everything in your strong opinion.
> Sorry I
> am taking off right now for vacation
Hi all,
Thanks Darij for bringing up the issue, and everyone for your
feedback! Here is my (strong for once) opinion on this issue. Sorry I
am taking off right now for vacations, so it's stated in a rush.
- I for myself usually prefer left composition for permutations (like
most combina
TypeError: unsupported operand parent(s) for '-': 'Symmetric group
algebra of order 5 over Rational Field' and 'Symmetric group algebra
of order 5 over Integer Ring'
I am disappoint...
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Hi Dima,
On Sat, Jul 13, 2013 at 1:26 PM, Dima Pasechnik wrote:
> IMHO it's a not as obsolete convention as you seem to imply; isn't e.g. Magma
> using the same convention as GAP?
> Not mentioning a lot of group theory literature...
I don't know anything about Magma, but what group theory litera
On 2013-07-12, darijgrinberg wrote:
> --=_Part_13473_7743396.1373672589533
> Content-Type: text/plain; charset=ISO-8859-1
>
> Hello!
>
> While trying to do computations in symmetric group algebras today, I was
> shocked by the fact that Sage uses the convention that a product \pi \psi
> of t
I think this point (Volker's) is a very good one: if the action is
to be a right action then it should be implemented as such, just as
many group theorists write "i\sigma" for the image of i under \sigma
with a right action. Persumably such right actions can be implemented
in Sage so one would w
Hello again,
thanks for the reactions! Good to see that I'm not the only one who is
having headaches with the current system.
On Saturday, 13 July 2013 05:21:58 UTC+2, Rob Beezer wrote:
>Breaking doctests is one thing, breaking user code is another.
>I've written some rather extensi
On Saturday, July 13, 2013 1:43:09 AM UTC+2, darijgrinberg wrote:
> There is a further issue lurking in the background here. It *is* possible
> to make Sage use the standard convention (first \psi, then \pi), namely by
> setting a global variable (see
> http://trac.sagemath.org/sage_trac/ticket
On Friday, July 12, 2013 11:58:13 PM UTC-4, David Joyner wrote:
> It boils down to defining a permutation group via a left action or
> a right action. Some people favor left-actions, some right-actions.
But the question is, how is this right action that you speak of implemented
in Sage?
sa
> I would not call this a bug either.
> It boils down to defining a permutation group via a left action or
> a right action. Some people favor left-actions, some right-actions.
> IMHO, it has the correct default behavior, but if someone wants to
> add methods to allow for an alternative defin
On Fri, Jul 12, 2013 at 11:21 PM, Rob Beezer wrote:
>
> On Friday, July 12, 2013 4:43:09 PM UTC-7, darijgrinberg wrote:
>>
>> Is this too barbarous a solution? Is the problem not much of a problem?
>
>
> Thanks for bringing this off Trac and to the wider audience. Some thoughts.
>
> While less th
I would be in favor of having the "sensible" notation, that is, change what
is currently in Sage.
With Sage-6.0 coming up there would be a natural transition point. It is
easy to have a warning shown the first time that you multiply two
permutations and not show it in DOCTEST_MODE. We would the
On Friday, July 12, 2013 4:43:09 PM UTC-7, darijgrinberg wrote:
>
> Is this too barbarous a solution? Is the problem not much of a problem?
>
Thanks for bringing this off Trac and to the wider audience. Some thoughts.
While less than ideal, I would not go so far as to call it a bug. But then
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