Maude-help mailing list

[Geert Janssen <geert AT watson.ibm.com>]

Dear Maude help mailing list,

I wondered whether it is possible to "subsort" the MachineInts.
I wanted to have a sort MachineNat that represents the natural numbers.
However, I tried using conditional membership statements to no avail.
What I did was this (in Core Maude):

   fmod MACHINE-NAT is
     protecting MACHINE-INT .
     sort MachineNat .
     subsort MachineNat < MachineInt .

     var N : MachineInt .
     cmb N : MachineNat if N >= 0 .
   endfm

Try reducing "0 >= 0" in this module ...
Anyway I am hoping that a guru can help me out here.
I have the feeling that it is simply impossible.

Geert Janssen