[isabelle-dev] An ARBITRARY question

2008-10-03 Thread Lawrence Paulson
What is the difference between  willundefined and arbitrary?
Larry

On 2 Oct 2008, at 18:44, Tobias Nipkow wrote:

 undefined and default are used in a specific way. If you do not  
 want
 that functionality (and accidental equalities), arbitrary is a good
 alternative.

 Tobias

 Florian Haftmann schrieb:
 Some years ago two further constants were introduces into HOL.thy:
 undefined and default.  The idea then was to divide the role of
 classical arbitrary on two shoulders:  undefined should be
 unspecified an could be used to fake partiality, whereas default  
 would
 be overloaded and could be instantiated on arbitrary types, which is
 useful e.g. for proof extraction.  Meanwhile the code dealing with
 unspecified case clauses and missing primrec equations etc. has  
 already
 switched from arbitrary to undefined.

 I would suggest to walk through and drop any remaining occurence of
 arbitrary by undefined.

 But perhaps arbitrary is too deep-rooted in HOL tradition to just  
 get
 rid of it.  Any further arguments against?

  Florian



 

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[isabelle-dev] An ARBITRARY question

2008-10-03 Thread Lawrence Paulson
Apologies for that garbled message. I meant,

What is the difference between undefined and arbitrary?

Larry

On 2 Oct 2008, at 18:44, Tobias Nipkow wrote:

 undefined and default are used in a specific way. If you do not  
 want
 that functionality (and accidental equalities), arbitrary is a good
 alternative.

 Tobias

 Florian Haftmann schrieb:
 Some years ago two further constants were introduces into HOL.thy:
 undefined and default.  The idea then was to divide the role of
 classical arbitrary on two shoulders:  undefined should be
 unspecified an could be used to fake partiality, whereas default  
 would
 be overloaded and could be instantiated on arbitrary types, which is
 useful e.g. for proof extraction.  Meanwhile the code dealing with
 unspecified case clauses and missing primrec equations etc. has  
 already
 switched from arbitrary to undefined.

 I would suggest to walk through and drop any remaining occurence of
 arbitrary by undefined.

 But perhaps arbitrary is too deep-rooted in HOL tradition to just  
 get
 rid of it.  Any further arguments against?

  Florian



 

 ___
 Isabelle-dev mailing list
 Isabelle-dev at mailbroy.informatik.tu-muenchen.de
 https://mailmanbroy.informatik.tu-muenchen.de/mailman/listinfo/isabelle-dev
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 Isabelle-dev at mailbroy.informatik.tu-muenchen.de
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[isabelle-dev] NEWS

2008-10-03 Thread Makarius
* Wrapper script for remote SystemOnTPTP service allows to use
sledgehammer without local ATP installation (Vampire etc.).  See also
ISABELLE_HOME/contrib/SystemOnTPTP and the VAMPIRE_HOME setting
variable. (By Fabian Immler, TUM)

(CVS note: need to move Distribution/contrib/ out of the way, if it exists 
already locally.)


[isabelle-dev] An ARBITRARY question

2008-10-03 Thread Tjark Weber
On Fri, 2008-10-03 at 14:14 +0200, Florian Haftmann wrote: 
 I also think that two would be better than three;  technically
 undefined is the same as arbitrary

Then what is the point of

  undefined_fun: undefined x = undefined

in HOL.thy?

Best,
Tjark



[isabelle-dev] An ARBITRARY question

2008-10-03 Thread Florian Haftmann
 Then what is the point of
 
   undefined_fun: undefined x = undefined
 
 in HOL.thy?

This is essentially pointless and is so soon to be dropped that I didn't
 take the effort to even point out to it in my emails, taking the risk
that somebody would have a look a the source ;-)

Florian

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