Description: TODO: fix comment. (Contributed by NM, 31-Jul-2013)
Ref | Expression | ||
---|---|---|---|
Hypotheses | cdlemk40.x | ⊢ 𝑋 = ( ℩ 𝑧 ∈ 𝑇 𝜑 ) | |
cdlemk40.u | ⊢ 𝑈 = ( 𝑔 ∈ 𝑇 ↦ if ( 𝐹 = 𝑁 , 𝑔 , 𝑋 ) ) | ||
Assertion | cdlemk40f | ⊢ ( ( 𝐹 ≠ 𝑁 ∧ 𝐺 ∈ 𝑇 ) → ( 𝑈 ‘ 𝐺 ) = ⦋ 𝐺 / 𝑔 ⦌ 𝑋 ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | cdlemk40.x | ⊢ 𝑋 = ( ℩ 𝑧 ∈ 𝑇 𝜑 ) | |
2 | cdlemk40.u | ⊢ 𝑈 = ( 𝑔 ∈ 𝑇 ↦ if ( 𝐹 = 𝑁 , 𝑔 , 𝑋 ) ) | |
3 | 1 2 | cdlemk40 | ⊢ ( 𝐺 ∈ 𝑇 → ( 𝑈 ‘ 𝐺 ) = if ( 𝐹 = 𝑁 , 𝐺 , ⦋ 𝐺 / 𝑔 ⦌ 𝑋 ) ) |
4 | ifnefalse | ⊢ ( 𝐹 ≠ 𝑁 → if ( 𝐹 = 𝑁 , 𝐺 , ⦋ 𝐺 / 𝑔 ⦌ 𝑋 ) = ⦋ 𝐺 / 𝑔 ⦌ 𝑋 ) | |
5 | 3 4 | sylan9eqr | ⊢ ( ( 𝐹 ≠ 𝑁 ∧ 𝐺 ∈ 𝑇 ) → ( 𝑈 ‘ 𝐺 ) = ⦋ 𝐺 / 𝑔 ⦌ 𝑋 ) |