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A paradox of the set theory 2.4

2016-08-31 21:19:03 | Mathematics
Let c={c1,c2…} be a countable set.
Add the propositional function p(x)=(x=c1)∨(x=c2)∨…(infinitely) to the usual language.
The closed logical formulas are still countable. You can use Gödel's theorem.
Let X be an axiom system by the language.
Let d be a free individual symbol. The mathematical axioms in X don't include d.
Put X" =X ∪{∀xp(x)}.
Theorem 1. X" isn't consistent.
Proof. If X" is consistent, X"∪{d≠c1}∪…∪{d≠cm} has a model Mm for which
Mm |= d=cm+1 and is consistent for ∀m∈N.
So X"∪{d≠c1}∪{d≠c2}∪…(infinitely) is consistent and has a mdel M by Göel's theorem.
M |= d≠c1, M |= d≠c2,…(infinitely)
The object domain of M is larger than c. But M |= ∀xp(x). This is contradiction.♦
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A paradox of the set theory 2.3

2016-08-17 01:35:06 | Mathematics
Let c={c1,c2,…} (ci≠ck for i≠k) be a countable set.
Add the propositional functions pm(x)=(x=cm)∨(x=cm+1)∨…(infinitely) (m∈N)
and q(x)=p2(x)∧p3∧…(infinitely) to the usual language.
The closed logical formulas are still countable. You can use Gödel's theorem.
Let X be a countable axiom system by the language.
Let d be a free individual symbol. The mathe matical axioms in X don't include d.
Theorem1. X isn't consistent.
Proof. pm+1(cm) is false. So ¬q(cm) is true.
If X is consistent, X∪{p1(d)}∪{¬q(d)}∪{d≠c1}∪…∪{d≠cm} has
a model Mm for which Mm |= d=cm+1 and is consistent for ∀m∈N.
So X∪{p1(d)}∪{¬q(d)}∪{d≠c1}∪{d≠c2}∪…(infinitely) is consistent and has
a model M by Gödel's theorem. pm(x)=p2(x)∧…∧pm(x)
So M |= p1(d) ⇔ (M |= d=c1)∨(M |= p2) ⇔ (M |= d=c1)∨(M |= d=c2)∨(M |= p2(d)∧p3(d))⇔…
Repeating this infinitely,you get (M |= d=c1)∨(M |= d=c2)∨…(infinitely)∨(M |= q(d)).
But M |= d≠c1, M |= d≠c2,…(infinitely),M |= ¬q(d). This is contradiction.♦
Theorem 2. You can trump up a proof of RH.
Proof. If the cm's are the zero points of ζ(x), RH=∀x(p1(x)→(Re x=1/2)∨(Im x=0)).
You are to use X.
X |- RH and X |- ¬RH by theorem 1.
Theorem 3. You can trump up proofs
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