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Metamath Proof Explorer

Theorem r1omtsk

Description: The set of hereditarily finite sets is a Tarski class. (The Tarski-Grothendieck Axiom is not needed for this theorem.) (Contributed by Mario Carneiro, 28-May-2013)

		Ref	Expression
	Assertion	r1omtsk	$⊢ R_{1} (ω) \in Tarski$

Proof

Step	Hyp	Ref	Expression
1		omina	$⊢ ω \in Inacc$
2		inatsk	$⊢ ω \in Inacc \to R_{1} (ω) \in Tarski$
3	1 2	ax-mp	$⊢ R_{1} (ω) \in Tarski$