Completeness of finite first order theories

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SUMMARY

Not every first order theory with finitely many axioms is automatically complete. The discussion highlights that an axiom schema, such as the separation axiom schema in Zermelo-Fraenkel set theory (ZFC), constitutes an infinite number of axioms, which complicates the completeness status. Robinson arithmetic serves as a definitive counterexample, alongside the empty theory over a non-empty language, which is also identified as a trivial counterexample.

PREREQUISITES
  • Understanding of first order logic
  • Familiarity with axiomatic systems
  • Knowledge of Zermelo-Fraenkel set theory (ZFC)
  • Basic concepts of model theory
NEXT STEPS
  • Research the properties of completeness in first order theories
  • Study Robinson arithmetic and its implications in model theory
  • Explore the structure and implications of axiom schemas in ZFC
  • Investigate the concept of trivial counterexamples in logical theories
USEFUL FOR

This discussion is beneficial for logicians, mathematicians, and students of mathematical logic who are exploring the nuances of completeness in first order theories.

Dragonfall
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Is every first order theory with finitely many axioms automatically complete? An axiom schema like that of ZFC's separation counts as an infinite number of axioms.
 
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Nevermind. Robinson arithmetic is a counterexample.
 
The empty theory over a non-empty language is the trivial counter-example.
 

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