Re: [isabelle] Proving formulae from separate sets of axioms



On Sep 3, 2009 9:39am, Alexander Krauss <krauss at in.tum.de> wrote:
Steve,




Can a formula describing the property a function should hold across

*several* theories? For example, I might have 2 theories T1.thy and T2.thy,

each with its own set of axioms. Can I prove something like there exists a

function F, variables x and y, such that F xy returns r1 in T1 and r2 in T2

and r1 != r2? T1 and T2 are each internally consistent, but together may be

inconsistent.




This is not possible. In some cases it is possible to localize axioms by just making them assumptions of some lemmas. The locale mechanism (see locale tutorial) gives some tool support for doing this.


If I localise axioms, then would I be able to check whether r1 != r2? Checking r1 != r2 seems to need to look at *both* sets of axioms. Also, can I check whether F is instantiated to the same thing on each side?

Thanks
Steve



Alex





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