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Description: A utility theorem for proving equivalence of "is a functor". (Contributed by Zhi Wang, 25-Sep-2025)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | funcf2lem2.b | ⊢ 𝐵 = ( 𝐸 ‘ 𝐶 ) | |
| Assertion | funcf2lem2 | ⊢ ( 𝐺 ∈ X 𝑧 ∈ ( 𝐵 × 𝐵 ) ( ( ( 𝐹 ‘ ( 1st ‘ 𝑧 ) ) 𝐽 ( 𝐹 ‘ ( 2nd ‘ 𝑧 ) ) ) ↑m ( 𝐻 ‘ 𝑧 ) ) ↔ ( 𝐺 Fn ( 𝐵 × 𝐵 ) ∧ ∀ 𝑥 ∈ 𝐵 ∀ 𝑦 ∈ 𝐵 ( 𝑥 𝐺 𝑦 ) : ( 𝑥 𝐻 𝑦 ) ⟶ ( ( 𝐹 ‘ 𝑥 ) 𝐽 ( 𝐹 ‘ 𝑦 ) ) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | funcf2lem2.b | ⊢ 𝐵 = ( 𝐸 ‘ 𝐶 ) | |
| 2 | funcf2lem | ⊢ ( 𝐺 ∈ X 𝑧 ∈ ( 𝐵 × 𝐵 ) ( ( ( 𝐹 ‘ ( 1st ‘ 𝑧 ) ) 𝐽 ( 𝐹 ‘ ( 2nd ‘ 𝑧 ) ) ) ↑m ( 𝐻 ‘ 𝑧 ) ) ↔ ( 𝐺 ∈ V ∧ 𝐺 Fn ( 𝐵 × 𝐵 ) ∧ ∀ 𝑥 ∈ 𝐵 ∀ 𝑦 ∈ 𝐵 ( 𝑥 𝐺 𝑦 ) : ( 𝑥 𝐻 𝑦 ) ⟶ ( ( 𝐹 ‘ 𝑥 ) 𝐽 ( 𝐹 ‘ 𝑦 ) ) ) ) | |
| 3 | 3simpc | ⊢ ( ( 𝐺 ∈ V ∧ 𝐺 Fn ( 𝐵 × 𝐵 ) ∧ ∀ 𝑥 ∈ 𝐵 ∀ 𝑦 ∈ 𝐵 ( 𝑥 𝐺 𝑦 ) : ( 𝑥 𝐻 𝑦 ) ⟶ ( ( 𝐹 ‘ 𝑥 ) 𝐽 ( 𝐹 ‘ 𝑦 ) ) ) → ( 𝐺 Fn ( 𝐵 × 𝐵 ) ∧ ∀ 𝑥 ∈ 𝐵 ∀ 𝑦 ∈ 𝐵 ( 𝑥 𝐺 𝑦 ) : ( 𝑥 𝐻 𝑦 ) ⟶ ( ( 𝐹 ‘ 𝑥 ) 𝐽 ( 𝐹 ‘ 𝑦 ) ) ) ) | |
| 4 | 2 3 | sylbi | ⊢ ( 𝐺 ∈ X 𝑧 ∈ ( 𝐵 × 𝐵 ) ( ( ( 𝐹 ‘ ( 1st ‘ 𝑧 ) ) 𝐽 ( 𝐹 ‘ ( 2nd ‘ 𝑧 ) ) ) ↑m ( 𝐻 ‘ 𝑧 ) ) → ( 𝐺 Fn ( 𝐵 × 𝐵 ) ∧ ∀ 𝑥 ∈ 𝐵 ∀ 𝑦 ∈ 𝐵 ( 𝑥 𝐺 𝑦 ) : ( 𝑥 𝐻 𝑦 ) ⟶ ( ( 𝐹 ‘ 𝑥 ) 𝐽 ( 𝐹 ‘ 𝑦 ) ) ) ) |
| 5 | fnov | ⊢ ( 𝐺 Fn ( 𝐵 × 𝐵 ) ↔ 𝐺 = ( 𝑥 ∈ 𝐵 , 𝑦 ∈ 𝐵 ↦ ( 𝑥 𝐺 𝑦 ) ) ) | |
| 6 | 5 | biimpi | ⊢ ( 𝐺 Fn ( 𝐵 × 𝐵 ) → 𝐺 = ( 𝑥 ∈ 𝐵 , 𝑦 ∈ 𝐵 ↦ ( 𝑥 𝐺 𝑦 ) ) ) |
| 7 | 1 | fvexi | ⊢ 𝐵 ∈ V |
| 8 | 7 7 | mpoex | ⊢ ( 𝑥 ∈ 𝐵 , 𝑦 ∈ 𝐵 ↦ ( 𝑥 𝐺 𝑦 ) ) ∈ V |
| 9 | 6 8 | eqeltrdi | ⊢ ( 𝐺 Fn ( 𝐵 × 𝐵 ) → 𝐺 ∈ V ) |
| 10 | 9 | adantr | ⊢ ( ( 𝐺 Fn ( 𝐵 × 𝐵 ) ∧ ∀ 𝑥 ∈ 𝐵 ∀ 𝑦 ∈ 𝐵 ( 𝑥 𝐺 𝑦 ) : ( 𝑥 𝐻 𝑦 ) ⟶ ( ( 𝐹 ‘ 𝑥 ) 𝐽 ( 𝐹 ‘ 𝑦 ) ) ) → 𝐺 ∈ V ) |
| 11 | simpl | ⊢ ( ( 𝐺 Fn ( 𝐵 × 𝐵 ) ∧ ∀ 𝑥 ∈ 𝐵 ∀ 𝑦 ∈ 𝐵 ( 𝑥 𝐺 𝑦 ) : ( 𝑥 𝐻 𝑦 ) ⟶ ( ( 𝐹 ‘ 𝑥 ) 𝐽 ( 𝐹 ‘ 𝑦 ) ) ) → 𝐺 Fn ( 𝐵 × 𝐵 ) ) | |
| 12 | simpr | ⊢ ( ( 𝐺 Fn ( 𝐵 × 𝐵 ) ∧ ∀ 𝑥 ∈ 𝐵 ∀ 𝑦 ∈ 𝐵 ( 𝑥 𝐺 𝑦 ) : ( 𝑥 𝐻 𝑦 ) ⟶ ( ( 𝐹 ‘ 𝑥 ) 𝐽 ( 𝐹 ‘ 𝑦 ) ) ) → ∀ 𝑥 ∈ 𝐵 ∀ 𝑦 ∈ 𝐵 ( 𝑥 𝐺 𝑦 ) : ( 𝑥 𝐻 𝑦 ) ⟶ ( ( 𝐹 ‘ 𝑥 ) 𝐽 ( 𝐹 ‘ 𝑦 ) ) ) | |
| 13 | 10 11 12 2 | syl3anbrc | ⊢ ( ( 𝐺 Fn ( 𝐵 × 𝐵 ) ∧ ∀ 𝑥 ∈ 𝐵 ∀ 𝑦 ∈ 𝐵 ( 𝑥 𝐺 𝑦 ) : ( 𝑥 𝐻 𝑦 ) ⟶ ( ( 𝐹 ‘ 𝑥 ) 𝐽 ( 𝐹 ‘ 𝑦 ) ) ) → 𝐺 ∈ X 𝑧 ∈ ( 𝐵 × 𝐵 ) ( ( ( 𝐹 ‘ ( 1st ‘ 𝑧 ) ) 𝐽 ( 𝐹 ‘ ( 2nd ‘ 𝑧 ) ) ) ↑m ( 𝐻 ‘ 𝑧 ) ) ) |
| 14 | 4 13 | impbii | ⊢ ( 𝐺 ∈ X 𝑧 ∈ ( 𝐵 × 𝐵 ) ( ( ( 𝐹 ‘ ( 1st ‘ 𝑧 ) ) 𝐽 ( 𝐹 ‘ ( 2nd ‘ 𝑧 ) ) ) ↑m ( 𝐻 ‘ 𝑧 ) ) ↔ ( 𝐺 Fn ( 𝐵 × 𝐵 ) ∧ ∀ 𝑥 ∈ 𝐵 ∀ 𝑦 ∈ 𝐵 ( 𝑥 𝐺 𝑦 ) : ( 𝑥 𝐻 𝑦 ) ⟶ ( ( 𝐹 ‘ 𝑥 ) 𝐽 ( 𝐹 ‘ 𝑦 ) ) ) ) |