Open nthiery opened 9 years ago
Description changed:
---
+++
@@ -1 +1,70 @@
Draft in finite-semigroup-nt.patch in the Sage-Combinat queue.
+
+Some notes:
+
+```
+class Semigroups.TransformationModules: # or .SetsWithAction
+ """modules where the action is by discrete transformations"""
+
+ class ParentMethods:
+ def actor(): ?
+ def semigroup(): ...
+ # Design goal: be left/right agnostic whenever possible
+ def action(self, x, s) or def action(self, s, x)
+
+class Semigroups.Finite:
+ class ParentMethods:
+ G.simple_modules(QQ): shorthand for G.algebras(QQ).simple_modules(QQ)?
+
+class Algebras.Modules:
+
+ class ParentMethods:
+ @abstract_method
+ def simple_modules() -> return a family indexed by below:
+ def simple_modules_index_set()
+
+ def projective_indecomposable_modules()
+ def cartan_matrix(self):
+ pass
+
+ def character(self):
+
+ def brauer_character(self): # modular case; do we want to identify them?
+
+ def character_value(self, s):
+ return
+
+ def class_function(self):
+ return self.character_value
+
+ # class_functions ? class_function_module? class_function_ring?
+ # cyclic_homology?
+ # trace_space Cyclic homology, second edition by Loday
+ def character_ring(self):
+
+ class FiniteDimensional:
+
+ class ParentMethods:
+
+ def representation():
+ Return the morphism S -> Hom(self, self)
+
+ @abstract_method # in the finite dimensional case
+ def representation_matrix(self, s):
+
+ @abstract_method
+ def isotypic_components():
+ """
+ Return the isotypic components of ``self``.
+
+ OUTPUT: a collection of submodules the internal direct
+ sum of which is ``self``.
+ """
+ #
+ induction / restriction
+
+ M.induce(LargerAlgebra) / M.induced_module(LargerAlgebra)
+
+ G.simple_modules(QQ): shorthand for G.algebras(QQ).simple_modules(QQ)
+```
+
Description changed:
---
+++
@@ -68,3 +68,12 @@
G.simple_modules(QQ): shorthand for G.algebras(QQ).simple_modules(QQ)
+Question: how to handle the case where the base ring of the module +does not match the base ring of the acting object? Example: complex +representations of real lie algebras + +```
Draft in finite-semigroup-nt.patch in the Sage-Combinat queue.
Some notes:
Question: how to handle the case where the base ring of the module does not match the base ring of the acting object? Example: complex representations of real lie algebras
CC: @tscrim
Component: algebra
Issue created by migration from https://trac.sagemath.org/ticket/18230