Theorem conss1

Description: Contrapositive law for subsets. (Contributed by Andrew Salmon, 15-Jul-2011)

	Ref	Expression
Assertion	conss1	⊢ ( ( V ∖ 𝐴 ) ⊆ 𝐵 ↔ ( V ∖ 𝐵 ) ⊆ 𝐴 )

Proof

Step	Hyp	Ref	Expression
1		difcom	⊢ ( ( V ∖ 𝐴 ) ⊆ 𝐵 ↔ ( V ∖ 𝐵 ) ⊆ 𝐴 )