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Description: Lemma for ackbij1 . (Contributed by Stefan O'Rear, 18-Nov-2014)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | ackbij.f | ⊢ 𝐹 = ( 𝑥 ∈ ( 𝒫 ω ∩ Fin ) ↦ ( card ‘ ∪ 𝑦 ∈ 𝑥 ( { 𝑦 } × 𝒫 𝑦 ) ) ) | |
| Assertion | ackbij1lem13 | ⊢ ( 𝐹 ‘ ∅ ) = ∅ |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | ackbij.f | ⊢ 𝐹 = ( 𝑥 ∈ ( 𝒫 ω ∩ Fin ) ↦ ( card ‘ ∪ 𝑦 ∈ 𝑥 ( { 𝑦 } × 𝒫 𝑦 ) ) ) | |
| 2 | 1 | ackbij1lem10 | ⊢ 𝐹 : ( 𝒫 ω ∩ Fin ) ⟶ ω |
| 3 | peano1 | ⊢ ∅ ∈ ω | |
| 4 | 2 3 | f0cli | ⊢ ( 𝐹 ‘ ∅ ) ∈ ω |
| 5 | nna0 | ⊢ ( ( 𝐹 ‘ ∅ ) ∈ ω → ( ( 𝐹 ‘ ∅ ) +o ∅ ) = ( 𝐹 ‘ ∅ ) ) | |
| 6 | 4 5 | ax-mp | ⊢ ( ( 𝐹 ‘ ∅ ) +o ∅ ) = ( 𝐹 ‘ ∅ ) |
| 7 | un0 | ⊢ ( ∅ ∪ ∅ ) = ∅ | |
| 8 | 7 | fveq2i | ⊢ ( 𝐹 ‘ ( ∅ ∪ ∅ ) ) = ( 𝐹 ‘ ∅ ) |
| 9 | ackbij1lem3 | ⊢ ( ∅ ∈ ω → ∅ ∈ ( 𝒫 ω ∩ Fin ) ) | |
| 10 | 3 9 | ax-mp | ⊢ ∅ ∈ ( 𝒫 ω ∩ Fin ) |
| 11 | in0 | ⊢ ( ∅ ∩ ∅ ) = ∅ | |
| 12 | 1 | ackbij1lem9 | ⊢ ( ( ∅ ∈ ( 𝒫 ω ∩ Fin ) ∧ ∅ ∈ ( 𝒫 ω ∩ Fin ) ∧ ( ∅ ∩ ∅ ) = ∅ ) → ( 𝐹 ‘ ( ∅ ∪ ∅ ) ) = ( ( 𝐹 ‘ ∅ ) +o ( 𝐹 ‘ ∅ ) ) ) |
| 13 | 10 10 11 12 | mp3an | ⊢ ( 𝐹 ‘ ( ∅ ∪ ∅ ) ) = ( ( 𝐹 ‘ ∅ ) +o ( 𝐹 ‘ ∅ ) ) |
| 14 | 6 8 13 | 3eqtr2ri | ⊢ ( ( 𝐹 ‘ ∅ ) +o ( 𝐹 ‘ ∅ ) ) = ( ( 𝐹 ‘ ∅ ) +o ∅ ) |
| 15 | nnacan | ⊢ ( ( ( 𝐹 ‘ ∅ ) ∈ ω ∧ ( 𝐹 ‘ ∅ ) ∈ ω ∧ ∅ ∈ ω ) → ( ( ( 𝐹 ‘ ∅ ) +o ( 𝐹 ‘ ∅ ) ) = ( ( 𝐹 ‘ ∅ ) +o ∅ ) ↔ ( 𝐹 ‘ ∅ ) = ∅ ) ) | |
| 16 | 4 4 3 15 | mp3an | ⊢ ( ( ( 𝐹 ‘ ∅ ) +o ( 𝐹 ‘ ∅ ) ) = ( ( 𝐹 ‘ ∅ ) +o ∅ ) ↔ ( 𝐹 ‘ ∅ ) = ∅ ) |
| 17 | 14 16 | mpbi | ⊢ ( 𝐹 ‘ ∅ ) = ∅ |