Description: The converse of a subset relation swaps arguments. (Contributed by Peter Mazsa, 1-Aug-2019)
Ref | Expression | ||
---|---|---|---|
Assertion | brcnvssr | ⊢ ( 𝐴 ∈ 𝑉 → ( 𝐴 ◡ S 𝐵 ↔ 𝐵 ⊆ 𝐴 ) ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | relssr | ⊢ Rel S | |
2 | 1 | relbrcnv | ⊢ ( 𝐴 ◡ S 𝐵 ↔ 𝐵 S 𝐴 ) |
3 | brssr | ⊢ ( 𝐴 ∈ 𝑉 → ( 𝐵 S 𝐴 ↔ 𝐵 ⊆ 𝐴 ) ) | |
4 | 2 3 | syl5bb | ⊢ ( 𝐴 ∈ 𝑉 → ( 𝐴 ◡ S 𝐵 ↔ 𝐵 ⊆ 𝐴 ) ) |