#13209: Fix some minor Cayley table documentation problems
---------------------------------------------+------------------------------
Reporter: kcrisman | Owner: joyner
Type: defect | Status: needs_work
Priority: trivial | Milestone: sage-5.6
Component: group theory | Resolution:
Keywords: cayley doc table beginner | Work issues:
Report Upstream: N/A | Reviewers: Karl-Dieter
Crisman
Authors: Kannappan Sampath | Merged in:
Dependencies: | Stopgaps:
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Comment (by knsam):
Replying to [comment:4 kcrisman]:
> > So, it does return a list of elements, not strings.
> Sure. But that's not what the keyword `elements` is referring to. Try
using that keyword and see what happens if you pass elements and not
strings.
Alright, I think there is no real issue with this one. Well, what I mean
is, since {{{(foo, bar)}}} stands for a tuple, having things like
{{{(1,2)(3,4)}}} scares Sage. Reasonable. I looked at how its overcome in
general:
{{{
sage: G = SymmetricGroup(5)
sage: sigma = G("(1,3) (2,5,4)")
}}}
which is basically coercion at play.
So, there are two work arounds:
1. Pass the elements as strings, because after all the code coerces them
into an element of the said group. *(done in the documentation)*
2. Or, suppose you have a group G. List its elements using {{{G.list()}}}.
Now determine the indices which you'd like to include in the list and use
a for loop to iterate.
Here's a test case:
{{{
sage: H = CyclicPermutationGroup(4)
sage: L = H.list()
sage: elts = []
sage: for i in {0, 2}:
... elts.append(L[i])
...
sage: elts
[(), (1,3) (2,4)]
sage: from sage.matrix.operation_table import OperationTable
sage: T = OperationTable(H, operator.mul, elements = elts)
sage: T
* a b
+----
a| a b
b| b a
}}}
So, does this solve the "thingy" issue? I will submit a patch for the
other two OperationTable docs. And, should this alternative way of passing
elements be documented?
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13209#comment:8>
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