Theorem bnj213

Description: First-order logic and set theory. (Contributed by Jonathan Ben-Naim, 3-Jun-2011) (New usage is discouraged.)

	Ref	Expression
Assertion	bnj213	$$⊢pred\left(X,A,R\right)\subseteq A$$

Proof

Step	Hyp	Ref	Expression
1		df-bnj14	$$⊢pred\left(X,A,R\right)=\left\{y\in A|yRX\right\}$$
2	1	ssrab3	$$⊢pred\left(X,A,R\right)\subseteq A$$