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Description: Move class substitution in and out of the converse of a relation. Version of csbcnvgALT without a sethood antecedent but depending on more axioms. (Contributed by Thierry Arnoux, 8-Feb-2017) (Revised by NM, 23-Aug-2018)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | csbcnv | ⊢ ◡ ⦋ 𝐴 / 𝑥 ⦌ 𝐹 = ⦋ 𝐴 / 𝑥 ⦌ ◡ 𝐹 |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | sbcbr | ⊢ ( [ 𝐴 / 𝑥 ] 𝑧 𝐹 𝑦 ↔ 𝑧 ⦋ 𝐴 / 𝑥 ⦌ 𝐹 𝑦 ) | |
| 2 | 1 | opabbii | ⊢ { 〈 𝑦 , 𝑧 〉 ∣ [ 𝐴 / 𝑥 ] 𝑧 𝐹 𝑦 } = { 〈 𝑦 , 𝑧 〉 ∣ 𝑧 ⦋ 𝐴 / 𝑥 ⦌ 𝐹 𝑦 } |
| 3 | csbopab | ⊢ ⦋ 𝐴 / 𝑥 ⦌ { 〈 𝑦 , 𝑧 〉 ∣ 𝑧 𝐹 𝑦 } = { 〈 𝑦 , 𝑧 〉 ∣ [ 𝐴 / 𝑥 ] 𝑧 𝐹 𝑦 } | |
| 4 | df-cnv | ⊢ ◡ ⦋ 𝐴 / 𝑥 ⦌ 𝐹 = { 〈 𝑦 , 𝑧 〉 ∣ 𝑧 ⦋ 𝐴 / 𝑥 ⦌ 𝐹 𝑦 } | |
| 5 | 2 3 4 | 3eqtr4ri | ⊢ ◡ ⦋ 𝐴 / 𝑥 ⦌ 𝐹 = ⦋ 𝐴 / 𝑥 ⦌ { 〈 𝑦 , 𝑧 〉 ∣ 𝑧 𝐹 𝑦 } |
| 6 | df-cnv | ⊢ ◡ 𝐹 = { 〈 𝑦 , 𝑧 〉 ∣ 𝑧 𝐹 𝑦 } | |
| 7 | 6 | csbeq2i | ⊢ ⦋ 𝐴 / 𝑥 ⦌ ◡ 𝐹 = ⦋ 𝐴 / 𝑥 ⦌ { 〈 𝑦 , 𝑧 〉 ∣ 𝑧 𝐹 𝑦 } |
| 8 | 5 7 | eqtr4i | ⊢ ◡ ⦋ 𝐴 / 𝑥 ⦌ 𝐹 = ⦋ 𝐴 / 𝑥 ⦌ ◡ 𝐹 |