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Metamath Proof Explorer

Theorem funcnvs4

Description: The converse of a length 4 word is a function if its symbols are different sets. (Contributed by AV, 10-Feb-2021)

Ref Expression
Assertion funcnvs4 ( ( ( ( 𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑉 ) ∧ ( 𝐶 ∈ 𝑉 ∧ 𝐷 ∈ 𝑉 ) ) ∧ ( ( 𝐴 ≠ 𝐵 ∧ 𝐴 ≠ 𝐶 ∧ 𝐴 ≠ 𝐷 ) ∧ ( 𝐵 ≠ 𝐶 ∧ 𝐵 ≠ 𝐷 ) ∧ 𝐶 ≠ 𝐷 ) ) → Fun ◡ ⟨“ 𝐴 𝐵 𝐶 𝐷 ”⟩ )

Proof

Step Hyp Ref Expression
1 c0ex ⊢ 0 ∈ V
2 1ex ⊢ 1 ∈ V
3 1 2 pm3.2i ⊢ ( 0 ∈ V ∧ 1 ∈ V )
4 2ex ⊢ 2 ∈ V
5 3ex ⊢ 3 ∈ V
6 4 5 pm3.2i ⊢ ( 2 ∈ V ∧ 3 ∈ V )
7 3 6 pm3.2i ⊢ ( ( 0 ∈ V ∧ 1 ∈ V ) ∧ ( 2 ∈ V ∧ 3 ∈ V ) )
8 7 a1i ⊢ ( ( ( 𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑉 ) ∧ ( 𝐶 ∈ 𝑉 ∧ 𝐷 ∈ 𝑉 ) ) → ( ( 0 ∈ V ∧ 1 ∈ V ) ∧ ( 2 ∈ V ∧ 3 ∈ V ) ) )
9 funcnvqp ⊢ ( ( ( ( 0 ∈ V ∧ 1 ∈ V ) ∧ ( 2 ∈ V ∧ 3 ∈ V ) ) ∧ ( ( 𝐴 ≠ 𝐵 ∧ 𝐴 ≠ 𝐶 ∧ 𝐴 ≠ 𝐷 ) ∧ ( 𝐵 ≠ 𝐶 ∧ 𝐵 ≠ 𝐷 ) ∧ 𝐶 ≠ 𝐷 ) ) → Fun ◡ ( { ⟨ 0 , 𝐴 ⟩ , ⟨ 1 , 𝐵 ⟩ } ∪ { ⟨ 2 , 𝐶 ⟩ , ⟨ 3 , 𝐷 ⟩ } ) )
10 8 9 sylan ⊢ ( ( ( ( 𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑉 ) ∧ ( 𝐶 ∈ 𝑉 ∧ 𝐷 ∈ 𝑉 ) ) ∧ ( ( 𝐴 ≠ 𝐵 ∧ 𝐴 ≠ 𝐶 ∧ 𝐴 ≠ 𝐷 ) ∧ ( 𝐵 ≠ 𝐶 ∧ 𝐵 ≠ 𝐷 ) ∧ 𝐶 ≠ 𝐷 ) ) → Fun ◡ ( { ⟨ 0 , 𝐴 ⟩ , ⟨ 1 , 𝐵 ⟩ } ∪ { ⟨ 2 , 𝐶 ⟩ , ⟨ 3 , 𝐷 ⟩ } ) )
11 s4prop ⊢ ( ( ( 𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑉 ) ∧ ( 𝐶 ∈ 𝑉 ∧ 𝐷 ∈ 𝑉 ) ) → ⟨“ 𝐴 𝐵 𝐶 𝐷 ”⟩ = ( { ⟨ 0 , 𝐴 ⟩ , ⟨ 1 , 𝐵 ⟩ } ∪ { ⟨ 2 , 𝐶 ⟩ , ⟨ 3 , 𝐷 ⟩ } ) )
12 11 adantr ⊢ ( ( ( ( 𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑉 ) ∧ ( 𝐶 ∈ 𝑉 ∧ 𝐷 ∈ 𝑉 ) ) ∧ ( ( 𝐴 ≠ 𝐵 ∧ 𝐴 ≠ 𝐶 ∧ 𝐴 ≠ 𝐷 ) ∧ ( 𝐵 ≠ 𝐶 ∧ 𝐵 ≠ 𝐷 ) ∧ 𝐶 ≠ 𝐷 ) ) → ⟨“ 𝐴 𝐵 𝐶 𝐷 ”⟩ = ( { ⟨ 0 , 𝐴 ⟩ , ⟨ 1 , 𝐵 ⟩ } ∪ { ⟨ 2 , 𝐶 ⟩ , ⟨ 3 , 𝐷 ⟩ } ) )
13 12 cnveqd ⊢ ( ( ( ( 𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑉 ) ∧ ( 𝐶 ∈ 𝑉 ∧ 𝐷 ∈ 𝑉 ) ) ∧ ( ( 𝐴 ≠ 𝐵 ∧ 𝐴 ≠ 𝐶 ∧ 𝐴 ≠ 𝐷 ) ∧ ( 𝐵 ≠ 𝐶 ∧ 𝐵 ≠ 𝐷 ) ∧ 𝐶 ≠ 𝐷 ) ) → ◡ ⟨“ 𝐴 𝐵 𝐶 𝐷 ”⟩ = ◡ ( { ⟨ 0 , 𝐴 ⟩ , ⟨ 1 , 𝐵 ⟩ } ∪ { ⟨ 2 , 𝐶 ⟩ , ⟨ 3 , 𝐷 ⟩ } ) )
14 13 funeqd ⊢ ( ( ( ( 𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑉 ) ∧ ( 𝐶 ∈ 𝑉 ∧ 𝐷 ∈ 𝑉 ) ) ∧ ( ( 𝐴 ≠ 𝐵 ∧ 𝐴 ≠ 𝐶 ∧ 𝐴 ≠ 𝐷 ) ∧ ( 𝐵 ≠ 𝐶 ∧ 𝐵 ≠ 𝐷 ) ∧ 𝐶 ≠ 𝐷 ) ) → ( Fun ◡ ⟨“ 𝐴 𝐵 𝐶 𝐷 ”⟩ ↔ Fun ◡ ( { ⟨ 0 , 𝐴 ⟩ , ⟨ 1 , 𝐵 ⟩ } ∪ { ⟨ 2 , 𝐶 ⟩ , ⟨ 3 , 𝐷 ⟩ } ) ) )
15 10 14 mpbird ⊢ ( ( ( ( 𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑉 ) ∧ ( 𝐶 ∈ 𝑉 ∧ 𝐷 ∈ 𝑉 ) ) ∧ ( ( 𝐴 ≠ 𝐵 ∧ 𝐴 ≠ 𝐶 ∧ 𝐴 ≠ 𝐷 ) ∧ ( 𝐵 ≠ 𝐶 ∧ 𝐵 ≠ 𝐷 ) ∧ 𝐶 ≠ 𝐷 ) ) → Fun ◡ ⟨“ 𝐴 𝐵 𝐶 𝐷 ”⟩ )