On 30 Jul 2011, at 17:18, Rob Arthan wrote:
> On 28 Jul 2011, at 18:10, Phil Clayton wrote:
>> There appears to be a bug in z_%mem%_seta_conv (see attached) when renaming
>> of bound variables is required but the bound variables are introduced by a
>> schema declaration.
> Yes. This needs to be fixed.
I hope the work-around I posted was useful.
I have been thinking about how to fix z_%mem%_seta_conv and can do so, but I
don't like the fix much, so I thought I would share it with you (and the list)
to see if we can come up with something neater. The fundamental problem is with
the conversion z_%exists%_intro_conv1 that turns HOL existentials of a suitable
form (specifically the form returned by z_%exists%_elim_conv2) into Z
existentials. z_%exists%_intro_conv1 doesn't know how to deal with the case
when substitutions have caused bound variables to be renamed - but that case
can fairly easily be fixed using z_dec_rename%down%s_conv. Unfortunately
z_dec_rename%down%s_conv depends on z_rename%down%s_conv which is defined in
the DTD043 module which depends on DTD042 (where z_%mem%_seta_conv lieves) and
DTD041 (where z_%exists%_intro_conv1 lives).
Teasing out the dependencies so that z_rename%down%s_conv can be moved into
DTD041 doesn't look very promising, but maybe I haven't tried hard enough.
There may be something I could do with the hated functors, but I don't know
what. So the only option is to have a hook in DTD041 for setting a conversion
that z_%exists%_intro_conv1 uses where z_dec_rename%down%s_conv is needed and
calling that hook (and then filtering it out of the signature) at the end of
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