I looked over Arthur Prior's formal logic tonight. Let V indicate a functioral variable of one argument. Prior's book indicates that from the following all 2-valued propositions can get derived. Actually, 2-5 in the following can get derived form 6. under substitution for V, substitution for variables, and detachment.
1. 1
2. C V 1 C V C00.
3. C V 1 C V C11.
4. C V 0 C V C10.
5. C V 1 C V C01.
6. C V 1 C V 0 V p.
I read about definitions getting expressed via a functioral variable " V " in two-valued logic last year and realized that definitions could get expressed in n-valued or infinite-valued logic via " V ". For example, we could express the definition of alternation (disjunction) in three-valued logic as follows:
Definition of Alternation: C V Apq V CCpqq.
I wondered if there existed a way to axiomatize a multi-valued logic via a protothetical axiom set such as the one given above by Prior. Since truth tables work for every single finite-valued logic, it turns out that every single finite-valued logic has a protothetical axiom scheme. Note that axiom 6 encompasses all truth values of two-valued logic.
For example of a prothetical axiom set of a multi-valued logic, three-valued Lukasiewicz logic has the following table for C and N:
C 0 1 2 N
0 2 2 2 2
1 1 2 2 1
2* 0 1 2 0
Thus, a protothetical axiom set for Lukasiewicz 3-valued logic is the following (compare the last axiom with axiom 6. of the above).
1. 1
2. C V 2 C V C00.
3. C V 2 C V C01.
4. C V 2 C V C02.
5. C V 2 C V N0.
6. C V 1 C V C10.
7. C V 2 C V C11.
8. C V 2 C V C12.
9. C V 1 C V N1.
10. C V 0 C V C20.
11. C V 1 C V C21.
12. C V 2 C V C22.
13. C V 0 C V N0.
14. C V 2 C V 1 C V 0 V p.
Saturday, October 4, 2014
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