Function and recdef work very differently. Function first disambiguates
the patterns, then it defines the graph of the function as an inductive
definition. Recdef turns the definitions into a single recursion equation with
case-expressions on the rhs.
Concerning the minimum number of equations: neither definition facility finds a
minimum, it is too hard: Alexander Krauss. Pattern minimization problems over
recursive data types. ICFP 2008.
Tobias
On 10/06/2015 23:19, Larry Paulson wrote:
We need to figure out how recdef does it. The minimum number of equations is
mathematically fixed, so recdef must be using conditional expressions or other
tricks.
Larry
On 9 Jun 2015, at 23:07, Gerwin Klein gerwin.kl...@nicta.com.au wrote:
I can confirm that, at least that side is simple.
Tobias’ point about avoiding exponential blowup is important, though. Might
still be too early to retire recdef entirely if it is substantially better for
some kinds of definitions, esp if they are in use (I think the recdef in Simpl
is one of these).
Cheers,
Gerwin
On 09.06.2015, at 11:27, Thomas Sewell thomas.sew...@nicta.com.au wrote:
I've had a quick scan over the NICTA repositories. It doesn't look like
there are any live original uses of recdef. There are recdefs in a copy
of Simpl-AFP, and in some backups of historical papers.
Short summary, NICTA doesn't have any stakes in recdef.
Cheers,
Thomas.
On 08/06/15 06:13, Makarius wrote:
On Sat, 6 Jun 2015, Gerwin Klein wrote:
On 06.06.2015, at 21:23, Makarius makar...@sketis.net wrote:
(2) 'defer_recdef' which is unused in the directly visible Isabelle
universe. So it could be deleted today.
This mailing list thread is an opportunity to point out dark matter
in the Isabelle universe, where 'defer_recdef' still occurs.
Otherwise I will remove it soon, lets say within 1-2 weeks.
Unused in our part of the dark matter universe as well.
The thread has shifted over to actual 'recdef'. Are there remaining
uses of 'recdef' in the NICTA dark matter?
So far I always thought the remaining uses in HOL-Decision_Procs are
only a reminder that there are other important applications.
Makarius
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