Logik wrote: ↑Sat Apr 13, 2019 7:36 am
PeteOlcott wrote: ↑Sat Apr 13, 2019 5:44 am
I was referring to this:
All formal systems of greater expressive power than arithmetic necessarily
have undecidable sentences.
I think I am starting to see your intention/objective here and I want to be sure we are on the same page in terms of your criteria for success.
Are you trying to lay down a set of axioms which guarantee that a system which adheres to them has both of these properties:
1. The system is more expressive than arithmetic.
2. The system is decidable.
A yes/no answer to would suffice here.
My second question would be that to which wtf alluded to above.
How do you evaluate "expressive power" ?
Given any two systems A and B, how do you evaluate the truth-value of the proposition: moreExpressive(A,B) ?
I only used the phrase (greater expressive power than arithmetic) to meet this specification:
The first incompleteness theorem states that in any consistent formal system F within which a certain amount of arithmetic can be carried out, there are statements of the language of F which can neither be proved nor disproved in F.
Raatikainen, Panu, "Gödel's Incompleteness Theorems", The Stanford Encyclopedia of Philosophy (Fall 2018 Edition),
The actual requirement is that the formal systems must directly have a provability
predicate (not faking one using diagonalization). This system would be consistent and
complete as long as it implements the Prolog inference model which is equivalent to
my three axioms of truth.
https://www.researchgate.net/publicatio ... finability