Theorem relssr

Description: The subset relation is a relation. (Contributed by Peter Mazsa, 1-Aug-2019)

	Ref	Expression
Assertion	relssr	⊢ Rel S

Proof

Step	Hyp	Ref	Expression
1		df-ssr	⊢ S = { ⟨ 𝑥 , 𝑦 ⟩ ∣ 𝑥 ⊆ 𝑦 }
2	1	relopabiv	⊢ Rel S