Belatedly: the constant behind HOL4's set comprehensions, GSPEC, is really just
a version of IMAGE, so if you can think of a monotonicity theorem for IMAGE,
that should be something you could transform to be suitable for GSPEC too.

Michael

On 04/04/13 00:56, Ramana Kumar wrote:
> I found a way around it: use a subset instead of the exact desired set.
> That is, make the premise
> tt s n1 n2 /\ (!n. n IN s ==> n < LENGTH v1 /\ n < LENGTH v2 /\ vv (EL n v1) 
> (EL
> n v2))
> 
> 
> On Wed, Apr 3, 2013 at 2:11 PM, Ramana Kumar <[email protected]
> <mailto:[email protected]>> wrote:
> 
>     I'm trying to write an inductive relation that relates equivalent
>     expressions in a programming language with respect to a context of pairs 
> of
>     variables assumed equivalent.
> 
>     I ran into this problem:
>     Exception raised at IndDefLib.Hol_reln:
>     at IndDefLib.Hol_mono_reln:
>     at IndDefRules.derive_strong_induction:
>     at Thm.EQ_MP
> 
>     I think what I need is a monotonicity rule for GSPEC, but I can't figure 
> out
>     what it should look like. Am I thinking in the right direction?
> 
>     Here is a very cut down example that exhibits the same problem:
> 
>     Hol_datatype`v = Cl of v list => num`
>     Hol_reln`(n IN s ==> tt s n n)`
> 
>     (* fails *)
>     Hol_reln`
>       (tt { n | n < LENGTH v1 /\ n < LENGTH v2 /\ vv (EL n v1) (EL n v2)} n1 
> n2
>        ==> vv (Cl v1 n1) (Cl v2 n2))`
> 
>     (* sanity check: works *)
>     Hol_reln`
>       n1 < LENGTH v1 /\ n1 < LENGTH v2 /\ vv (EL n1 v1) (EL n1 v2) /\
>       (n1 = n2)
>       ==> vv (Cl v1 n1) (Cl v2 n2)`
> 
>     In my real example, vv and tt would be mutually recursive - does that make
>     it significantly harder?
> 
> 
> 
> 
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