Theorem oldmaded

Description: An element of an old set is an element of a made set. (Contributed by Scott Fenton, 27-Feb-2026)

	Ref	Expression
Hypothesis	oldmaded.1	$$⊢\phi \to A\in \mathrm{Old}\left(B\right)$$
Assertion	oldmaded	$$⊢\phi \to A\in M\left(B\right)$$

Proof

Step	Hyp	Ref	Expression
1		oldmaded.1	$$⊢\phi \to A\in \mathrm{Old}\left(B\right)$$
2		oldssmade	$$⊢\mathrm{Old}\left(B\right)\subseteq M\left(B\right)$$
3	2 1	sselid	$$⊢\phi \to A\in M\left(B\right)$$