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Ptolemy: fixes in the documentation.
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unhyperbolic committed Oct 26, 2023
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15 changes: 8 additions & 7 deletions doc_src/ptolemy_examples1.rst
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Expand Up @@ -146,7 +146,7 @@ Compute the matrices for a representation

**Remark:** Requires SnapPy 2.3 or later.

Given a solution as above, we can take a word in the fundamental group and get its image under the representation using ``evaluate_word``. Here, we do it for the two generators::
Given a solution as above, we can take a word in the fundamental group and get its image under the representation using :py:meth:`~snappy.ptolemy.coordinates.PtolemyCoordinates.evaluate_word`. Here, we do it for the two generators::

>>> M = Manifold("m003")
>>> sol = M.ptolemy_variety(2).retrieve_solutions()[0]
Expand All @@ -156,16 +156,17 @@ Given a solution as above, we can take a word in the fundamental group and get i
[[Mod(x, x^2 - x - 1), Mod(x, x^2 - x - 1)],
[Mod(-x, x^2 - x - 1), Mod(-1, x^2 - x - 1)]]

By default, this word is with respect to the presentation of the fundamental group that SnapPy computes when given no further arguments. Thus, we expect the identity matrix when we evaluate a relator (for PSL(*N*, **C**) the diagonal element will be an *N*-th root of unity)::
By default, this word is with respect to the unsimplified presentation of the fundamental group. Thus, we expect the identity matrix when we evaluate a relator (for PSL(*N*, **C**) the diagonal element will be an *N*-th root of unity)::

>>> M.fundamental_group()
>>> M.fundamental_group(simplify_presentation=False)
Generators:
a,b
a,b,c
Relators:
abAAbabbb
>>> sol.evaluate_word('abAAbabbb')
BCaC
AbCbA
>>> sol.evaluate_word('BCaC')
[[Mod(1, x^2 - x - 1), 0], [0, Mod(1, x^2 - x - 1)]]

We revisit computing the matrices :ref:`here <ptolemy-detailed-example-matrices>` to explain how to use a different presentation of the fundamental group.

**Remark:** The matrices are currently returned as a list of list of pari ``POLMOD`` objects. In the future, the ptolemy module should return the matrices as sage matrices over a `sage NumberField <http://doc.sagemath.org/html/en/reference/number_fields/sage/rings/number_field/number_field.html>`_.
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4 changes: 2 additions & 2 deletions doc_src/ptolemy_examples3.rst
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Expand Up @@ -101,7 +101,7 @@ And here the same example retrieving solutions from the database::
Computing the matrices for a different presentation
---------------------------------------------------

The ``fundamental_group`` method of a SnapPy triangulation can yield different presentations by supplying optional arguments such as ``simplify_presentation`` and ``minimize_number_of_generators``. If we have a word in one of these presentations and want to evaluate its image under the representation, we need to supply the presentation as follows::
The :py:meth:`~snappy.Triangulation.fundamental_group` method of a SnapPy triangulation can yield different presentations by supplying optional arguments such as ``simplify_presentation`` and ``minimize_number_of_generators``. If we have a word in one of these presentations and want to evaluate its image under the representation, we need to supply the presentation as follows::

>>> M=Manifold("m003")
>>> sol = M.ptolemy_variety(2).retrieve_solutions()[0]
Expand Down Expand Up @@ -129,7 +129,7 @@ Again, we can check that the representation actually assigns the identity to all
Computing the images of the peripheral curves for a representation
------------------------------------------------------------------

The object returned by ``fundamental_group`` also contains words for the peripheral curves of a manifold. We can compute the corresponding matrices::
The object returned by :py:meth:`~snappy.Triangulation.fundamental_group` also contains words for the peripheral curves of a manifold. We can compute the corresponding matrices::

>>> M = Manifold("m003")
>>> G = M.fundamental_group()
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