[isabelle-dev] Sort Annotation vs. Class Context for Lemmas

Tobias Nipkow nipkow at in.tum.de
Fri Jan 21 15:27:50 CET 2011

One issue can be that if some sort involves multiple type classes, the
corresponding class may not have been defined. That is the one advantage
of sorts: you can create conjunctions/intersection of type classes on
the fly.


Tjark Weber schrieb:
> Hi,
> I noticed that numerous lemmas in HOL that refer to class constants are
> stated at the top level (using implicit or explicit sort annotations),
> rather than in the corresponding class context (see, for instance,
> Compl_lessThan in HOL/SetInterval.thy).  If I am not mistaken, this
> means the corresponding lemma is not available in the context of the
> class, which seems unfortunate.  Is this merely a legacy issue, or are
> there genuine reasons for stating these lemmas with sort annotations?
> Kind regards,
> Tjark
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