Highest Priority

================

- better lookup mechanism for quotient definition

  (see fixme in quotient_term.ML)

- check needs to be fixed in mk_resp_arg (quotient_term.ML),

  see test for (_, Const _)

- clever code in quotiet_tacs.ML needs to be turned into

  boring code

- comment about regularize tactic needs to be adapted

- Check all the places where we do "handle _"

  (They make code changes very difficult: I sat 1/2

  a day over a simplification of calculate_inst before

  I understood things; the reason was that my exceptions

  where caught by the catch all. There is no problem

  with throwing and handling exceptions...it just must

  be clear who throws what and what is thrown.)

Higher Priority

===============

- If the user defines twice the same quotient constant,

  for example funion, then the line 

    val Free (lhs_str, lhs_ty) = lhs

  in quotient_def raises a bind exception.

- If the constant definition gives the wrong definition

  term, one gets a cryptic message about absrep_fun

- have FSet.thy to have a simple infrastructure for 

  finite sets (syntax should be \<lbrace> \<rbrace>,

  look at Set.thy how syntax is been introduced)

- Handle theorems that include Ball/Bex. For this, would 

  it help if we introduced separate Bex and Ball constants 

  for quotienting?

- The user should be able to give quotient_respects and 

  preserves theorems in a more natural form.

Lower Priority

==============

- Maybe a quotient_definition should already require

  a proof of the respectfulness (in this way one

  already excludes non-sensical definitions)

- accept partial equivalence relations

- think about what happens if things go wrong (like

  theorem cannot be lifted) / proper diagnostic 

  messages for the user

- inductions from the datatype package have a strange

  order of quantifiers in assumptions.

- wrapper for lifting ... to be used as an attribute

- find clean ways how to write down the "mathematical"

  procedure for a possible submission (Peter submitted 

  his work only to TPHOLs 2005...we would have to go

  maybe for the Journal of Formalised Mathematics)

- add tests for adding theorems to the various thm lists

- Maybe quotient and equiv theorems like the ones for

  [QuotList, QuotOption, QuotPair...] could be automatically

  proven?

- Examples: Finite multiset.

- The current syntax of the quotient_definition is

      "qconst :: qty"

      as "rconst"

  Is it possible to have the more Isabelle-like

  syntax

      qconst :: "qty"

      as "rconst"

  That means "qconst :: qty" is not read as a term, but

  as two entities.