Changes between Version 63 and Version 64 of CategoriesRoadMap

Timestamp:

01/21/11 01:49:22 (2 years ago)

Author:

nthiery

Comment:

--

CategoriesRoadMap

@@ -170 +170 @@
 - Roadmap for after:
   * Add more examples of parents (HELP!):
-    Ultimately, this should be for all categories,
+    Ultimately, this should be for all categories.
     Those are needed urgently:
     * Modules (for doctests for __mul__ / __rmul__ / ...)
@@ -178 +178 @@
     e.g.: Semigroups??, Semigroups().example()??
     Semigroups().parent_class?, Semigroups.element_class?
-  * Add ObjectMethods for category objects that are not parents.
+  * Add ObjectMethods for category objects that are not parents?
   * Choose, implement, and use systematically a mantra for testing if P is an algebra (over whatever ring):
     - P in Algebras
@@ -199 +199 @@
   * __init_add__
   * Writing and linking to generic documentation
-  * Standardize the functorial constructions, and streamline with
-    variants (finite / finite dimensional / graded / abstract / ...)
+
+  * Add support for automatic join for full subcategories (finite /
+    finite dimensional / graded / ...). E.g.
+    join(FiniteSets() and Groups()) should be FiniteGroups().
+
+  * join and meet are misnomers: since we speak of subcategories, then
+    the implicit order is A <= B if A is a subcategory of B. So join
+    and meet should be exchanged. Maybe it's too late for backward
+    compatibility. Then maybe we could use "intersect" instead of
+    join. For meet, there does not seem to be an obvious name, but
+    it's also very seldom used at the user interface, so the backward
+    compatibility issue is not that relevant.
+
   * Hom is *not* a functorial construction. This works for now, but
     the design and user interface needs to be discussed for the long
@@ -208 +219 @@
     where the specializations (A x b) -> C and and (a x B) -> C are
     morphisms for possibly different categories (see also #8900)
+
   * Defining new inline operators, at least within the sage interpreter
   * Convention for the order in super_categories (see primer)