magic/dat/BTW.show

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608 B
Text

B Axioms 1 - 8 as for FD.
9. ((A -> B) & (A -> C)) -> (A -> (B & C))
10. ((A -> C) & (B -> C)) -> ((A v B) -> C)
Rules 1 - 2, 8 - 12 as for FD.
Rules 6 and 7 replaced by the above axioms.
Rules 3 - 5 replaced by:
4'. A -> B ==> (C -> A) -> (C -> B)
5'. A -> B ==> (B -> C) -> (A -> C)
DW is B with rule 8 replaced by the axiom form:
Axiom 11. (A -> ~B) -> (B -> ~A)
TW is DW with rules 4' and 5' replaced by the axiom forms:
Axiom 12. (A -> B) -> ((C -> A) -> (C -> B))
13. (A -> B) -> ((B -> C) -> (A -> C))