Characterization of consistency. Prove that for a σ-theory T the following are equivalent: (1) T is consistent. (2) T ⊬ F , where F := ¬T and T := ∀x(x = x). (3) T ⊬ ϕ for some σ-formula ϕ.

Algebra & Trigonometry with Analytic Geometry
13th Edition
ISBN:9781133382119
Author:Swokowski
Publisher:Swokowski
Chapter10: Sequences, Series, And Probability
Section10.4: Mathematical Induction
Problem 25E
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Characterization of consistency. Prove that for a σ-theory T the following are equivalent:
(1) T is consistent.
(2) T ⊬ F , where F := ¬T and T := ∀x(x = x).
(3) T ⊬ ϕ for some σ-formula ϕ. 

Characterization of consistency. Prove that for a o-theory T the following are equiva-
lent:
(1) T is consistent.
(2) TF, where F
(3) Tro for some o-formula q.
=
¬T and T :=\x(x = x).
Transcribed Image Text:Characterization of consistency. Prove that for a o-theory T the following are equiva- lent: (1) T is consistent. (2) TF, where F (3) Tro for some o-formula q. = ¬T and T :=\x(x = x).
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