The game is to prove GCD in NonNegativeInteger (NNI). We would like to use the 'nat' theorems from the existing library but extract those theorems automatically from Axiom sources at build time.
Axiom's NNI inherits from a dozen Category objects, one of which is BasicType which contains two signatures: ?=?: (%,%) -> Boolean ?~=?: (%,%) -> Boolean In the ideal case we would decorate BasicType with the existing definitions of = and ~= so we could create a new library structure for the logic system. So BasicType would contain theorem = (a, b : Type) : Boolean := ..... theorem ~= (a, b : Type) : Boolean := .... These theorems would be imported into NNI when it inherits the signatures from the BasicType Category. The collection of all of the theorems in NNI's Category structure would be used (hopefully exclusively) to prove GCD. In this way, all of the theorems used to prove Axiom source code would be inheritied from the Category structure. Unfortunately it appears the Coq and Lean will not take kindly to removing the existing libraries and replacing them with a new version that only contains a limited number of theorems. I'm not yet sure about FoCaL but I suspect it has the same bootstrap problem. Jeremy Avigad (Lean) made the suggestion to rename these theorems. Thus, instead of =, the supporting theorem would be 'spad=' (spad is the name of Axiom's algebra language). Initially this would make Axiom depend on the external library structure. Eventually there should be enough embedded logic to start coding Axiom theorems by changing external references from = to spad= everywhere. Axiom proofs would still depend on the external proof system but only for the correctness engine, not the library structure. This will minimize the struggle about Axiom's world view (e.g. handling excluded middle). It will also organize the logic library to more closely mirror abstract algebra. Comments, suggestions? Tim
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