Finding a sentence and a graph model

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SUMMARY

The discussion focuses on defining a V-sentence φ that possesses arbitrarily large finite models, specifically ensuring that for any finite model G, the cardinality |G| is even. Additionally, participants explore the challenge of identifying a finite graph G that maintains an even cardinality yet does not model the defined sentence φ. A critical hint provided emphasizes that for every finite graph, the number of vertices with an odd degree is even, supporting the proof through induction on the number of edges.

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  • Understanding of V-sentences in model theory
  • Knowledge of graph theory, particularly properties of vertices and edges
  • Familiarity with induction proofs
  • Basic concepts of finite models in mathematical logic
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sara15
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can we define a V-sentence phi such that phi has arbitrarily large finite models and , for any finite model G , |G| is even . and then finding a finite graph G such that |G| is even and G doesnot model the sentence phi that I mentioned above.
please explain it to me
 
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Hint: For every finite graph, the number of its vertices which have odd degree is even.
Hint for Proof of Hint: Induction on the number of edges.
 

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